Tried a new kind of basecase division.
Switched to new divrem basecase.
Move divrem fixup into macro.
Removed a couple of duplicated macros.
Updated copyright notices.
Changed the name of a macro.
Removed mullow_n_basecase.asm, as the interface is useless.
Fast sb_divappr_q code.
Added new sb_div_q code, updated some comments and copyright notices.
Switched to new divrem32 macro and did some minor housekeeping.
Added dc_divappr_q and fixed sb_divappr_q, general code clean up.
Switch all precomputed inverses to new ones.