Improve ERB dependency detection.

The current implementation can't handle some special cases of oddly-formatted Ruby. Now we are able to detect them:

* Multi-line arguments on the `render` call
* Strings containing quotes, e.g. `"something's wrong"`
* Multiple kinds of identifiers - instance variables, class variables and globals
* Method chains as arguments for the `render` call

Also, this fix reduces the rate of "false positives" which showed up when we had calls/access to identifiers containing `render`, like `surrender` and `rendering`.
Avoid scanning multiple render calls as a single match.

Each chunk of text coming after `render` is now handled individually as a possible list of arguments.
Update changelog
don't establish a new connection when testing with `sqlite3_mem`.

This fixes broken `rake test_sqlite3_mem` suite for Active Record.
The problem is that that the old database with the schema is lost
when establishing a new connection. Upon reconnting we are left
with a blank database and tests down the line start failing.
Use single quotes in generated files
"string" isn't a valid column type for ActiveRecord

Conflicts:
	activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb
Updated comment to mention the enum mapping class method [ci skip]
directly create the ARel AST

rather than allocating a new Relation, just make the AST directly
rm dup code

https://github.com/rails/rails/blob/e64a83cdbd3ce836f3339c600c1006b20c23d8fd/activerecord/test/cases/relation/merging_test.rb#L80-91
Merge pull request #13713 from chulkilee/use-single-quotes

Use single quotes in generated files
Unify changelog entries about single quotes [ci skip]
Avoid converting :on option to array twice when defining commit/rollback callbacks
Get rid of unused TransactionError constant

This has been added 9 years ago in
a677da209b16f43198b3485dda89dce862fb9bfb, and removed 6 years ago in
38f8252e2d0a109d1b833d6b289cd989e7bfffe4.
methods are defined right after the module_eval, so we don't need to do
any line number maths
no need to `return skip` in tests. `skip` is enough.
tests without transactional fixtures need to cleanup afterwards.

This fixes test order issues.
use `teardown` for cleanup, not `setup`.

This solves order dependent issues where the last test
leaked the query cache state. This resulted in the following error:

```
QueryCacheExpiryTest#test_cache_is_expired_by_habtm_delete [test/cases/query_cache_test.rb:275]:
not all expectations were satisfied
unsatisfied expectations:
- expected exactly twice, invoked once: #<ActiveRecord::ConnectionAdapters::SQLite3Adapter:0x7f93e0c65838>.clear_query_cache(any_parameters)
```
isolate class attribute assignment in `migration_test.rb`

This makes the tests inside `migration_test.rb` order independent.
The assignments to `Reminder.table_name_prefix` and `Reminder.table_name_suffix`
previously leaked and had impact on following test cases.

This patch isolates the assignments on a throw-away subclass.
we have `with_env_tz` as global test helper. Remove duplicate.
reset column information after fiddling with `Encoding.default_internal`

This solves order depndent problems in `base_test.rb`. The leaked column
information crashed test cases using the `Weird` class later on:

```
  2) Error:
BasicsTest#test_group_weirds_by_from:
SyntaxError: /Users/senny/Projects/rails/activemodel/lib/active_model/attribute_methods.rb:387: invalid hex escape
... attribute_before_type_cast("\x{A4CA}\x{A4DE}\x{A4A8}", *arg...
...                               ^
/Users/senny/Projects/rails/activemodel/lib/active_model/attribute_methods.rb:387: invalid hex escape
...te_before_type_cast("\x{A4CA}\x{A4DE}\x{A4A8}", *args)
...                               ^
/Users/senny/Projects/rails/activemodel/lib/active_model/attribute_methods.rb:387: invalid hex escape
...e_type_cast("\x{A4CA}\x{A4DE}\x{A4A8}", *args)
...                               ^
    /Users/senny/Projects/rails/activemodel/lib/active_model/attribute_methods.rb:385:in `module_eval'
    /Users/senny/Projects/rails/activemodel/lib/active_model/attribute_methods.rb:385:in `define_proxy_call'
    /Users/senny/Projects/rails/activemodel/lib/active_model/attribute_methods.rb:294:in `block in define_attribute_method'
    /Users/senny/Projects/rails/activemodel/lib/active_model/attribute_methods.rb:285:in `each'
    /Users/senny/Projects/rails/activemodel/lib/active_model/attribute_methods.rb:285:in `define_attribute_method'
    /Users/senny/Projects/rails/activemodel/lib/active_model/attribute_methods.rb:252:in `block in define_attribute_methods'
    /Users/senny/Projects/rails/activemodel/lib/active_model/attribute_methods.rb:252:in `each'
    /Users/senny/Projects/rails/activemodel/lib/active_model/attribute_methods.rb:252:in `define_attribute_methods'
    /Users/senny/Projects/rails/activerecord/lib/active_record/attribute_methods.rb:72:in `block in define_attribute_methods'
    /Users/senny/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/mutex_m.rb:73:in `synchronize'
    /Users/senny/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/mutex_m.rb:73:in `mu_synchronize'
    /Users/senny/Projects/rails/activerecord/lib/active_record/attribute_methods.rb:69:in `define_attribute_methods'
    /Users/senny/Projects/rails/activerecord/lib/active_record/attribute_methods.rb:174:in `method_missing'
    /Users/senny/Projects/rails/activerecord/lib/active_record/attribute_assignment.rb:45:in `public_send'
    /Users/senny/Projects/rails/activerecord/lib/active_record/attribute_assignment.rb:45:in `_assign_attribute'
    /Users/senny/Projects/rails/activerecord/lib/active_record/attribute_assignment.rb:32:in `block in assign_attributes'
    /Users/senny/Projects/rails/activerecord/lib/active_record/attribute_assignment.rb:26:in `each'
    /Users/senny/Projects/rails/activerecord/lib/active_record/attribute_assignment.rb:26:in `assign_attributes'
    /Users/senny/Projects/rails/activerecord/lib/active_record/core.rb:458:in `init_attributes'
    /Users/senny/Projects/rails/activerecord/lib/active_record/core.rb:191:in `initialize'
    /Users/senny/Projects/rails/activerecord/lib/active_record/inheritance.rb:30:in `new'
    /Users/senny/Projects/rails/activerecord/lib/active_record/inheritance.rb:30:in `new'
    /Users/senny/Projects/rails/activerecord/lib/active_record/persistence.rb:33:in `create'
    test/cases/base_test.rb:646:in `test_group_weirds_by_from'
```