synchronization with beta branch
Merge branch 'master' into beta

Conflicts:
	src/org/geometerplus/fbreader/formats/DjvuExternalFormatPlugin.java
	src/org/geometerplus/fbreader/formats/ExternalFormatPlugin.java
	src/org/geometerplus/fbreader/formats/PdfExternalFormatPlugin.java
	src/org/geometerplus/fbreader/formats/PluginImage.java
repackaging
Merge branch 'master' into beta
introduces BuiltinFormatPlugin class
Merge branch 'master' into beta