Updated guides with latest method [ci skip]

for blank?
fixed file name references [ci skip]
Updated guides with latest method [ci skip]
Removed doc of removed method diff [ci skip]
Fix the SQLite gem name
Add packages list for ArchLinux [ci skip]

Add the packages required on Arch Linux when setting up the development
dependencies
grab executable from rubygems

As done here d7fc97d3f90c0e30865d32ce202658f03248cacc
Revert "Fix the SQLite gem name"

This reverts commit 700c6c65bcce17d4c61423ceaef031bcbe203337.

Bot the `sqlite3` and `sqlite3-ruby` gems exist.
https://rubygems.org/gems/sqlite3
https://rubygems.org/gems/sqlite3-ruby

In fact, they both point to the same github repository.
https://github.com/luislavena/sqlite3-ruby

However, the last one hasn't been released since 2011, while the first
one keeps getting regular releases.
Refix my misreading of the diff

sorry @robin850.
Thanks @fxn
Add a SQL example for `not` [ci skip]

To share a certain logic across other examples, let's add a sample SQL
code generated by the given Ruby code
Use hyphenated version of assert_url [ci skip]
Fixes typo in Object#try!
fix order dependent test related to migration

If the order in which tests are executed is changed then test fails.
This commit ensures that all migrations are run before ensuring that
there are no pending migration.
make test order independent by resetting timezone
Fix lixml2 to libxml2 [ci skip]
reset default timezone and make test order independent
make test not depend on order

`NestedThroughAssociationsTest` adds records to `member_details` table.
When test performs `@member_details[0]` then the order of record
is not guaranteed. Hence it is best to start with a clean slate by
deleting unwanted records.
Changed stylesheet load order in the stylesheet manifest generator.
Using markdown-style code quotes
Cleanup of class_name

Don't think class name is needed as by default belongs_to :select will be linked to Select class.