- refactor VxVector-like struct. split their declaration and implementatio because their implementation is too long. and occupy too much space in header.
- refactor VxVector struct generator. use jinja2 template engine, rather ran hand-written format string to make it is easy to read (although it still tough when first reading).
- add unary operator overloading for VxVector-like struct.
- add some VxMatrix functions which are essential to CKCamera.
- rename VxMatrix::ResetToIdentity to VxMatrix::SetIdentity to make it same as original Virtools SDK.
- the spaceship overloading with auto return value still may have bugs. please watch it carefully.
- fix the wrong reference in CMake script which install lib target into wrong directory.
- add file, change CMake script and modify header file for preparing develop of CKLight and CKCamera.
- fix doc typo.
