Updated Russian translation
Updated Galician translations
tests: don't use some deprecated properties
Updated Lithuanian translation
view: don't leak the buffer
view: various code clean-up

- GTK_SOURCE_IS_VIEW checks also for NULL.

- No need for "!= FALSE" when returning a "guint : 1" struct field. For
setting it is needed, but not for using it.

- Various other things.
File loading and saving

New public classes: GtkSourceEncoding, GtkSourceFileLoader and
GtkSourceFileSaver.
There are also new properties in GtkSourceBuffer.

https://bugzilla.gnome.org/show_bug.cgi?id=721016
Move some enum types to gtksourcetypes.h
build: rename helper library private -> core
encoding: comment unused functions
GtkSourceEncoding documentation
Some code improvements
GtkSourceFile, the come back
Move mount_operation_factory to GtkSourceFile
Add missing GI annotation
FileSaver: add setting: ignore invalid chars
File saving: check if the file is externally modified

Store the modification time in GtkSourceFile, and update the value on
each file loading and saving.
FileSaver: flags instead of boolean properties
FileSaver: use IGNORE_MODIFICATION_TIME flag
Make GtkSourceMountOperationFactory introspection-friendly

There was a GI warning.