sin_lookup: fix typo in init function name
sin_lookup: clean up widely scoped and unneeded includes

Including files unnecessarily makes it harder to build these
files for unit tests.
ut sin_lookup: add basic unit test for sin_lookup.c

Functions are validated against host's sinf/cosf implementations.

Only the (default) FLASH_TABLE variant is currently tested.
Merge pull request #476 from solidgoldbomb/math-unit-tests2

Add unit tests for sin_lookup.c