Refactorized inefficient usage of std::string and const char[] (part 2).
Refactorization: Use templates and rValue references
-> Performance gain of up to 15% on entire checking time (depends on setup; Result was checked with VS12 (x64), matchcompiled version, ran on tinyxml and cppcheck itself)
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.
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%)
Removed DJGPP/__sun hack in check.h
Refactorizations:
- Rearranged members of Value to reduce structures size
- Removed redundant ctor of Value
- Fixed VS warning in tokenize.cpp
Refactorization: Moved condition in Token::tokAt() out of loop.
Benchmark code