THRIFT-2757: py - checkIntegerLimits optimized

Client: Python
libgenerate extracted from thrift executable so compiler specific unit tests can be added
compiler: IndentKeeper extracted from t_generator

* tests added for IndentKeeper
* t_generator movd a little bit towards meeting SRP
* IndentKeeper can be reused by lower level generator
     (like MethodGenerator)
* IndentGuard added
* ScopeGuard added
compiler: C++ generator refactoring started - operator<< generation made more 'clean'
compiler: OutputGenerator added

wraps output stream and keeps indent and stream to indent in one place
compiler: some Makefiles split

more towards single library/target - single Makefile
compiler - cpp11: HeaderFileGenerator added
compiler - cpp11: EnumGenerator added
compiler - cpp11: FieldGenerator added
compiler - cpp11: IncludesScanner extracted from FieldsGenerator
compiler - parse objects extracted to separate library
compiler - cpp11: IncludesGenerator extracted

FieldsGenerator getting lightier
compiler - cpp11: TypeGenerator extracted from FieldsGenerator
compiler - cpp11: FieldGenerator complete

for now
compiler - cpp11: typedef generation added
compiler - Makefile clean up

don't know why, but without it 'make check' was not resolving
dependencies properly. Now everything build in proper order
compiler - cpp11: OperatorEqGenerator added
compiler - cpp11: SwapGenerator added
compiler - cpp11: added initial struct header generation
-Wextra -Werror enabled in compiler libs