Add emuext pragma and associated instructions. This provides two emulator specific instructions ("log" and "debug") enabled by the "emuext" pragma. This is from a patch provided by tim Lindner <tlindner@macmess.org>. From Tim's submission: ---- I stole the whole patch from Erik Gavriluk. I hope he doesn't mind. :) The two instructions are "debug" and "log". They are enabled with pragmas. I also added them to the manual. Hopefully all is well. ---- Said Erik Gavriluk <erik@bombfactory.com> in response: ...happy to see them picked up in mainline (if you choose to do so)....

--- a/lwasm/pragma.c	Tue Jul 24 17:41:04 2018 -0600
+++ b/lwasm/pragma.c	Thu Nov 01 23:00:00 2018 -0600
@@ -75,6 +75,7 @@
 	{ "newsource", "nonewsource", PRAGMA_NEWSOURCE },
 	{ "nooldsource", "oldsource", PRAGMA_NEWSOURCE },
 	{ "operandsizewarning", "nooperandsizewarning", PRAGMA_OPERANDSIZE },
+	{ "emuext", "noemuext", PRAGMA_EMUEXT },
 	{ 0, 0, 0 }
 };