[Reduction] #563-568: Floating-point emulator initialization

Finally - and there was indeed no way around switching to JWlink, as ALINK
v1.6 refuses to link the TH01 executables with a nondescript "Undefined base
seg" message once nec_fpinit.asm is included.
[Reduction] #569: xcvt

... and even with EMUL being set up and working, TASM still needs to be hacked
into actually emitting emulator calls for certain instructions.