Merge pull request #3253 from qifun/issue3249-fix

Fix #3249
[cs] UnaryNegation is -, not !
[cs] Do not make non-hxgen type parameters on functions to be called as hxgen types
strip abstract this argument for argument completion (see #3256)
Add abstract method completion test (closes #3256)
Also hide @:noComplete members in Visual Studio
Merge branch 'csharp-noComplete' into qifun