Add class scoped_switch_to_sym_language_if_auto.

The class scoped_switch_to_sym_language_if_auto allows to switch in a scope
the current language to the language of a symbol when language mode is
set to auto.

2018-11-20  Philippe Waroquiers  <philippe.waroquiers@skynet.be>

	* language.h (scoped_switch_to_sym_language_if_auto): New class.
2 files changed