Fixes Issue 648 - Expand template mixins in ddoc.
fix Issue 9305 - Ugly Ddoc for default template lambda expressions
Fix Issue 9195 - Should not be able to index a pointer in safed

This prevents indexing a pointer in @safe code unless the index is known at compile time to be zero.
add BT pattern to optimizer
add test case for BT patterns
Merge pull request #1483 from WalterBright/b8

add BT pattern to optimizer
Merge pull request #1482 from yebblies/issue9195

Issue 9195 - Should not be able to index a pointer in safed
Merge pull request #1481 from 9rnsr/fix9305

Issue 9305 - Ugly Ddoc for default template lambda expressions
Merge pull request #1480 from AndrejMitrovic/Fix648

Issue 648 - Expand template mixins in ddoc
fix D2 pull #1480
revert last couple of pulls
revert failing test cases