Gui update - buttons disabled while running encryption/decryption.
Gui update - added preview.
Merge branch 'master' of https://github.com/io-project/meerkat
Updated import/export plugin.
Improve generics usage in interfaces. Refactoring implementation to implement fixed interfaces.
Merge remote-tracking branch 'remotes/origin/master' into validators-api

Conflicts:
	src/main/java/meerkat/modules/gui/IGuiImplementation.java
	src/main/java/meerkat/modules/import_export/dropbox/DropboxExport.java
	src/main/java/meerkat/modules/import_export/dropbox/DropboxImport.java