implemented NORMAL math routine, added more stubs

c64/basic/,stubs_math/b7b5.STRVAL.s

@@ -0,0 +1,19 @@
+// #LAYOUT# STD *       #TAKE
+// #LAYOUT# *   BASIC_0 #TAKE
+// #LAYOUT# *   *       #IGNORE
+
+//
+// Math package - imports string to FAC1 - XXX: what about spaces?
+//
+// Input:
+// - .A needs to be loaded with string length
+// - string address in $22/$23
+//
+// See also:
+// - https://www.c64-wiki.com/wiki/Floating_point_arithmetic
+//
+
+// XXX provide implementation
+
+STRVAL:
+	STUB_IMPLEMENTATION()