Make variables in Transit() more localized
Make Stack::Push() force inline in normal path
Use lookup table for Tokenize()
Remove stack size limit feature

It is not very useful for iterative parsing as the worst case of heap
size is O(n) where n is number of character in JSON, for the worst
synthetic cases. This is reasonable and should not create stack overflow
security problem as in recursive parsing.
Cleanup code
Force inline some suitable functions.
In iterative parsing, always use SizeType to prevent potential alignment problem on some platforms.
Define RAPIDJSON_FORCEINLINE for gcc

Performance boost a lot!
Add perf test cases for document using iterative parsing
Fix parse error message
Merge remote-tracking branch 'origin/master' into IterativeParseOptimization
Merge pull request #81 from miloyip/IterativeParseOptimization

Iterative parse optimization