Merge branch 'maint'

* maint:
  warnings: introduce -Wdeprecated in the usage info
  errors: prefix the output with "error: "
  errors: indent "invalid value for %define" context
  errors: indent "%define var" redefinition context
  errors: indent "symbol redeclaration" context
  errors: indent "result type clash" error context

Conflicts:
	src/complain.c
	src/muscle-tab.c
	src/reader.c
	src/symtab.c
	tests/conflicts.at
	tests/input.at
	tests/named-refs.at
	tests/output.at
	tests/skeletons.at

src/getargs.c

@@ -326,13 +326,14 @@ Warning categories include:\n\
   `yacc'            incompatibilities with POSIX Yacc\n\
   `conflicts-sr'    S/R conflicts (enabled by default)\n\
   `conflicts-rr'    R/R conflicts (enabled by default)\n\
+  `deprecated'      obsolete constructs\n\
   `other'           all other warnings (enabled by default)\n\
   `all'             all the warnings\n\
   `no-CATEGORY'     turn off warnings in CATEGORY\n\
   `none'            turn off all the warnings\n\
   `error'           treat warnings as errors\n\
-\n\
 "), stdout);
+      putc ('\n', stdout);
 
       fputs (_("\
 THINGS is a list of comma separated words that can include:\n\