Implementing matmath class and other improvements

[kalwalt]

In this PR i will implement these classes:

• matmath
• linalg
• refactoring of cache

I am refactoring part of the code, for example jsfeatNext.cache is not extended internally in the jsfeatNext.js but it is imported outside from an external class. This make coding a lot easier and avoid some pitfalls. Actually for every classes jsfeatNext is imported (circular import!) i would avoid this and instead create separate classes or function to be imported for every functionality.

I refactored the code and plus i added a new JSFEAT_CONSTANTS where store all constants, and data_type that include the three functions _get_data_type _get_channel _get_data_type_size. Other classes added:

• matrix_t (external class)
• pyramid_t (external class)
• new pyrdown and warp_affine inside imgproc