Compiler messaging mega patch. va_yyreport() is now the main C-level dispatcher for compiler messages. It also handles the automatic conversion of type errors to warnings in compat mode. Consolidated the location for the implementation of most of the yy*-messaging functions to program.c. Added yytype_report(). Changed APIs for yyexplain_*(). Moved the definitions of REPORT_* from pike_compiler.h to program.h. va_yyerror() and low_yyerror() are no more. Most type-system messages should now be marked with the appropriate subsystem. Reenabled the typechecking for sscanf and sprintf() now that errors are converted into warnings in compat mode. Rev: src/language.yacc:1.425 Rev: src/las.c:1.413 Rev: src/las.h:1.79 Rev: src/modules/sprintf/sprintf.c:1.153 Rev: src/pike_compiler.h:1.14 Rev: src/pike_types.c:1.337 Rev: src/pike_types.h:1.118 Rev: src/program.c:1.702 Rev: src/program.h:1.248 Rev: src/sscanf.c:1.184