flight.js: Return flight reference from searchForPlane()
flight.js: Reduced array lookups in setPlaneOnMap() function
flight.js: Reduced array lookups in hidePlaneOnMap() functions
flight.js: Pass flight to set/hidePlaneOnMap() functions
js: Added slFlightCollection module
flight.js: Removed trivial functions
flight.js: Pass placeholder to initPhasesTable() function
Merge branch 'master' into flight-collection

Conflicts:
	skylines/templates/flights/map.jinja
	skylines/templates/flights/view.jinja
	skylines/templates/tracking/map.jinja
	skylines/templates/tracking/view.jinja
import_mwp: clear table before import
import_mwp: no explicit conversion to unicode
controllers.api: append degree symbol only on numerical wind directions
mapserver/mwp: show wind direction arrow only if wind direction is known
import_mwp: parse field 'mainwinddi' instead of using the value of 'weather_dir'

"WeatherDir wurde nur kurzzeitig bei den letzten Versionen
zusätzlich erzeugt und fällt in Zukunft wieder weg.
Ich würde euch empfehlen

MainWindDirection
in Zukunft Main_Wind_Direction

zu verwenden."
Merge pull request #26 from Turbo87/flight-collection

JS FlightCollection class