Split out into a C function and use normal naming for variables.
Added my rebuild script to speed things up.
Fixed comment.
Move to-rad conversion in the call, so that we can reuse each C-function.
Removed useless file.
Move radius conversion out of the helper function, so we can use it for other things too.
Added the fraction_along_gc_line() function.

This is the code behind http://drck.me/gc-a98.