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/crlf.asm

@@ -0,0 +1,9 @@
+; This file is encoded with DOS CR+LF line endings!
+
+DEF s EQUS "Hello, \
+world!"
+assert !strcmp("{s}", "Hello, world!")
+
+DEF t EQUS """Hello,
+world!"""
+assert !strcmp("{t}", "Hello,\nworld!")