Add cffi support; refactor related modules.
Set safe conversion rule for Array with contiguous layout to any layout
Improve dispatcher speed for one definition function
Fix boolean argument and refactor related functions
Update example
Expose short type names
Allow implicit i64 to f64
Use opt3 by default.
Fix invalid math.pi math.e typing
Allow triggering of dispatcher compilation at use into compiling code.
Add constant array support
Ufuncs should shared typing context with regular CPU functions