changed IMap to an interface (fixed issue #1629)

git-svn-id: http://haxe.googlecode.com/svn/trunk@6441 f16182fa-f095-11de-8f43-4547254af6c6
didn't mean to commit that

git-svn-id: http://haxe.googlecode.com/svn/trunk@6442 f16182fa-f095-11de-8f43-4547254af6c6
added haxe.ds.WeakMap

git-svn-id: http://haxe.googlecode.com/svn/trunk@6443 f16182fa-f095-11de-8f43-4547254af6c6
handle abstracts in EFunction (fixed issue #1689)

git-svn-id: http://haxe.googlecode.com/svn/trunk@6444 f16182fa-f095-11de-8f43-4547254af6c6