Added support for explicit conversion operators and added new pass which will create implicit and explicit conversion operators out of single argument constructors.

Conflicts:
	src/Generator/Passes/CheckAmbiguousFunctions.cs
	src/Generator/Passes/CheckOperatorsOverloads.cs
Introduced new property Method.IsExplicit in AST.
Constructor to conversion operator pass makes use of newly introduced Method.IsExplicit property.
Removed the const restriction in the constructor to conversion operator pass.
Re-generated the parser bindings with IsExplicit.
Added IsExplicit support to ASTConverter.