Implement modes switching

From now, only one key (T) is needed. Each press of
this key will switch to next enabled module.
Cleanup the code
Fix compile error
Merge branch 'ruian' into plpis

Conflicts:
	data/cs.lang
	data/en.lang
	po/cs.po
	po/files_list
	po/tracer.po
	src/org/openstreetmap/josm/plugins/tracer/TracerPlugin.java
Add LPIS module
Convert JSON parsing from org.json to javax.json
Merge branch 'ruian' into plpis
Remove obsolete library
Add LPIS module - finalization