Added status icon plugin

Signed-off-by: Roland Sommer <rol@ndsommer.de>
Merge pull request #1 from rsommer/status

Add status-icon support via plugin.
Touchup
Add separator after current clipboard selection in popups
Examples for more config options
Identation and code reshuffeling
Add option parsing (for providing a config file)
Code style
Create a HistoryContainer interface and move current code to its standard implementation
Make the HistoryContainer a regular, configurable plugin
Fall back to DummyHistory if no history is configured
Return after finding a HistoryContainer so we do not always fall back to the DummyHistory
Add signal support
Restructure code to make use of glib signals and split up code
Add tray icon support
Pimp snippet and actions plugin
Make klemmbrett not error out when clipboard-contents is set to None
Fix typo leading to a syntax error
Disable duplicate setting of primary buffer in _check()
Interpolate current clipboard contents into statement