stage1: add @sin @cos @exp @exp2 @ln @log2 @log10 @fabs @floor @ceil @trunc @round

and expand @sqrt

This revealed that the accuracy of ln is not as good as the current algorithm in
musl and glibc, and should be ported again.

v2: actually include tests
v3: fix reversal of in and out arguments on f128M_sqrt()
    add test for @sqrt on comptime_float
    do not include @nearbyInt() until it works on all targets.