Add runAll.py to run the test suite

Modify symbol.Class.resolveFieldOrder:
- handle overloaded functions while calculating the offset
	of each member of a class

Modfiy translate.Translater.fillVTableEntries:
- handle overloaded functions while building VTable

Modify translate.Translater.createFuncty:
- replace the function names with function signatures

Add FuncUtils:
- getCallFunction:
	Get a suitable function symbol for a specific call
		or return an error
	Return value is of type getCallFunctionReturn
- getArgListString:
	Get the string of a function with function name and parameter list

Modify the process of building the symbol table:
- visitMethodDef:
	Modify the function table with this name
		instead of inserting a single function
	Add the signature of this function into the table
- checkOverride:
	Check overrides of overloaded functions
- isMainClass:
	Issue errors if main function is overloaded

Modify type checks:
- call FuncUtils.getCallFunction to get the symbol
	of this function call

Modify symbol Function:
- toSignature:
	Return the signature of this function
- conflictArgList:
	Check whether this function is conflicted with another

Add errors:
- AmbiguousNewDeclarationError:
	Ambiguous new declarations
		with the same parameter list but different return values
- ConflictMainError:
	Multiple main functions
- MethodCallAmbiguousError:
	Ambiguous method matches the method call
- NoMatchMethodError:
	No method matches the call
- RedefinitionError:
	Redefine the same function
- VarOverrideMethodError:
	Try to override the method with a variable

Add CommonUtils:
- copyList: shallow copy a List

- Add symbol FunctionTable to store the overload table of a function
- Add function isFunctionTable in Symbol to check the type