#5875 fix 'lib/checksizeof.cpp:142:26: runtime error: member call on null pointer of type 'Token'. Improve error handling in CheckSizeof::checkSizeofForPointerSize()
Fixed #5867 (invalid debug warnung: Scope::checkVariable : varid0)
Fixed #5890 - crash: wesnoth desktop_util.cpp / unicode.hpp.
Fixed #5885 - fsanitize=undefined: signed integer overflow: 2147483647 + 1 cannot be represented in type 'int' in lib/tokenize.cpp.
MathLib: Added missing testcase for incdec.
Refactorizations optimizing std::string usage:
1) Added global const std::string emptyString; object. It is used for:
- Empty string passed to a function, which takes the parameter by reference
-> Avoids constructor call (std::string::string(""))
=> Reduces binary size (25% for testrunner.exe, 5% for cppcheck-core.dll)
=> Avoids unnecessary calls
- Functions, that return a string by reference
-> Even functions that return an empty string in some branches can return by reference now.

2) Added overloads for TestFixture::assertEquals for the most common use cases:
-> Moves conversion from const char[] to std::string into a function, reducing code duplication in binary.

Conflicts:
	lib/errorlogger.h
Updated solution to VS12
Visual Studio: Use testsuite.h as precompiled header (compiled into testrunner.cpp)
-> Reduces build time of project testrunner by 13 seconds (16%)
Refactorization: Moved condition in Token::tokAt() out of loop.

Conflicts:
	lib/tokenize.cpp
Benchmark code
Use C++11 std::sto* instead of std::ato* where appropriate (emulated in cxx11emu.h)

Conflicts:
	lib/mathlib.cpp

Conflicts:
	lib/checkbufferoverrun.cpp
Further include cleanup
Implemented AST validation, fixed lots of bugs in the AST:
- Support new and delete
- Properly handle "..."
- References and rValue references as function parameters
- Destructor definitions