When we check two type objects equality, we should use Type::equals instead of directly pointer comparison.
Default args and arg identifiers are now volatile information in TypeFunction.

1. The extra informations would be kept after semantic analysis for function pointer and delegate types. But merging type would strip all the extras from the type structure, then cache the stripped copy into.

2. The types has extra informations cannot be named. In other words, AliasDeclaration would always strip the aliased type. This rule also works for Template Type Parameter, and fixes issue 3646 well.

3. CondExp would strip them from the type of its result.
Improved fix for Issue 3866 - anonymous delegate with default parameters cross-talks to another anonymous delegate

This reverts commit acc22ce25db42facfe4917aeceabd28a410f4c95,
and moves original test into runnable/functype.d
fix Issue 3646 - Default values of function arguments are ignored when instantiating a template.
fix Issue 8579 - Default parameter appears a part of typeof().stringof of a function variable
Fix CppMangle issue

Use merge2() result for function argument types mangling.
fix Issue 10462 - interface thunk doesn't preserve EBX
fix Issue 10475 - destructor is called on 'for' loop variable even when initialization failed
fix Issue 4899 - Ddoc: Warnings about stray parens do not include file and line numbers for module comments

Add ModuleDeclaration::loc and use it for "Stray paren" ddoc warning.
Merge pull request #2278 from WalterBright/fix10462

fix Issue 10462 - interface thunk doesn't preserve EBX
Merge pull request #2286 from 9rnsr/fix10475

Issue 10475 - destructor is called on 'for' loop variable even when initialization failed
Merge pull request #2291 from 9rnsr/fix4899

Issue 4899 - Ddoc: Warnings about stray parens do not include file and line numbers for module comments
fix Issue 10254 - Purity correctness is broken with constructor
Merge pull request #2135 from 9rnsr/fix10254

Issue 10254 - Purity correctness is broken with constructor
add switch jump tables for Win64, Linux, FreeBSD, and OSX
Merge pull request #2285 from WalterBright/jmptab-for-linux

add switch jump tables for Win64, Linux, FreeBSD and OSX
add more switch tests
Merge pull request #2293 from WalterBright/add-testswitch

add more switch tests
Merge pull request #1102 from 9rnsr/improveDefArgs

Improve default argument processing
fix issue 10542 - implicitly generated class ctor doesnt inherit base
class ctor attributes