Implement BREAK to exit REPT and FOR loops

Fixes #684

include/asm/fstack.h

@@ -75,6 +75,7 @@ void fstk_RunMacro(char const *macroName, struct MacroArgs *args);
 void fstk_RunRept(uint32_t count, int32_t nReptLineNo, char *body, size_t size);
 void fstk_RunFor(char const *symName, int32_t start, int32_t stop, int32_t step,
 		     int32_t reptLineNo, char *body, size_t size);
+bool fstk_Break(void);
 
 void fstk_Init(char const *mainPath, size_t maxRecursionDepth);
 

include/asm/lexer.h

@@ -56,7 +56,8 @@ enum LexerMode {
 	LEXER_NORMAL,
 	LEXER_RAW,
 	LEXER_SKIP_TO_ELIF,
-	LEXER_SKIP_TO_ENDC
+	LEXER_SKIP_TO_ENDC,
+	LEXER_SKIP_TO_ENDR
 };
 
 void lexer_SetMode(enum LexerMode mode);