implemented another batch of small floating point routiines

c64/basic/math/bc2b.interop

@@ -0,0 +1,4 @@
+This is an important floating point math routine, documented in many places.
+
+Example code utilizing this routine:
+- https://github.com/irmen/prog8/blob/master/compiler/res/prog8lib/c64flt.p8