Math - Vector 2, Vector 3 and Matrix 3x3

[phy1um]

Math systems work as follows:

• Vector/Matrices are backed by boring C arrays
• Lua wraps these in an object compatible with "ps2.buffer" metatable
• Matrix/Vector operations are defined in C in terms of C arrays
• Lua bindings are wrapped in pure Lua utility functions which pass the underlying Lua ps2.buffer to C functions for manipulation
• Operations override the LHS parameter, eg A:add(B) mutates A. To achieve A = B + C we first make A a copy of B, then evaluate A:add(C)

We can create pipelines of math operations in Lua, but then trivially port those to C later if performance is a problem.

Missing/Todo:

• [x] Cleanup eg/math.lua tests
• [x] Fix tostring()