Fixes Issue 7408 - __traits(compiles) should work on builtin template instance properties.
Merge pull request #1456 from AndrejMitrovic/Fix7408

Issue 7408 - __traits(compiles) should work on builtin template instance properties
Merge pull request #1508 from mxfm/master

[trivial] Add src/vergen to .gitignore 
fix unintended reversions
Merge pull request #1509 from WalterBright/b13

recognize BT pattern
remove bt() builtin
Merge pull request #1510 from WalterBright/b14

remove bt() builtin