Update for 2.9.2.

* NEWS: Updated.
* README: Updated version and dependencies.

NEWS

+2.9.2:
+* Added SourceUndoManager, SourceCompletionWords and updated SourceBuffer.
+  (Krzesimir Nowak)
+* Added vfuncs to SourceCompletionProposal and SourceCompletionProvider.
+  (Krzesimir Nowak)
+* Documentation: Documented SourceUndoManager, SourceCompletionWords and new
+  methods in SourceBuffer.
+  (Krzesimir Nowak)
+
 2.9.1:
 * Documentation: Documented all stuff.
   (Krzesimir Nowak)

README

-C++ wrapper for gtksourceview, version 2.9.1.
+C++ wrapper for gtksourceview, version 2.9.2.
 
 Current dependencies:
 - to build a library from tarball:
-  * gtksourceview >= 2.9.4
+  * gtksourceview >= 2.9.7
   * gtkmm >= 2.12.0
 - to build a documentation:
   * same as above and tools required by mm-common, that are: