Add more test coverage for RGBASM (#1256)

This also fixes two bugs: `-1 >>> 32` was -1 not 0, and `macro_FreeArgs` should have been called but wasn't.

test/asm/invalid-numbers.asm

@@ -0,0 +1,17 @@
+; no digits
+def x = $
+def x = `
+
+; too large
+def x = 9_876_543_210
+def x = $f_0000_0000
+def x = &400_0000_0000
+def x = %1_00000000_00000000_00000000_00000000
+def x = 65537.0q16
+
+; no precision suffix
+def x = 3.14q
+
+; invalid precision suffix
+def x = 3.14q40
+