Merge remote-tracking branch 'origin/maint'

Merge remote-tracking branch 'origin/maint'

* origin/maint:
  yacc.c: always initialize yylloc
  scanner: issue a single error for groups of invalid characters
  tests: formatting changes
  doc: one of the fixes for an ambiguous grammar was ambiguous too
  doc: fix the dangling else with precedence directives
  doc: prefer "token" to TOKEN
  doc: formatting changes
  scanner: use explicit "ignore" statements

Conflicts:
	src/scan-gram.l