Release pqiv 2.5

pqiv 2.5 introduces some new features:

* Backends may now be built as shared libraries, and the dependencies
  become weak dependencies: If e.g. magickwand is installed, the
  backend is used. If it isn't, the library cannot be loaded and is
  ignored.
* A libarchive backend allows to read comic books (*.cb?)
* A new concept is introduced to abstract away key bindings: Actions
  allow to control pqiv. Key bindings are configurable. It is possible
  to bind multiple actions to a single key. It is also possible to bind
  actions to key sequences like in VIM, e.g. "gn" to goto the next and
  "gp" to goto the previous image.

Other changes include the usual minor bug fixes and work arounds. See
the changelog or git log for details.

This commit closes #58.

README.markdown

@@ -128,7 +128,7 @@ Known bugs
 Changelog
 ---------
 
-pqiv 2.5 (wip; see #58)
+pqiv 2.5
  * Added a configure option to build the backends as shared libraries
  * Added a configure option to remove unneeded/unwanted features
  * Added --watch-files to make the file-changed-on-disk action configurable

pqiv.h

@@ -29,7 +29,7 @@
 #include "lib/bostree.h"
 
 #ifndef PQIV_VERSION
-#define PQIV_VERSION "2.4"
+#define PQIV_VERSION "2.5"
 #endif
 
 #define FILE_FLAGS_ANIMATION      (guint)(1)