Fix std.BigInt bug #9548 plus other new discovered bugs.
Removed unused stream abstraction
fix issue 10167
immutable should be an enum
Merge pull request #1306 from WalterBright/toenum

immutable should be an enum
Merge pull request #1304 from majiang/patch-2

fix issue 10167
Merge pull request #1273 from Diggsey/master

fix issue 9979 - regex back-looper bug
Merge pull request #1231 from Safety0ff/master

Fix std.BigInt bug #9548 plus other new discovered bugs.
fix for calling .array() on ranges in CTFE
Merge pull request #1305 from dymk/ctfe-array

fix for calling .array() on ranges in CTFE
Merge branch 'master' into win32-bindings
Fixed std.bitmanip unit test so that the intended behaviour of checking both endian types is the actual behaviour