Merge pull request #19 from Turbo87/elevation

Adding elevation data
controllers/flight: Added missing srid parameter
assets: Use v2.3.0 of the bootstrap-dropdown script

v2.2.0 is causing problems on the iPad
map.js: hide mwp layer when bing layer is active
map.js: remove obsolete transparent property from XYZ layers
map-click-handler.js: Calculate bounding box only when needed
GraphicLayerSwitcher: Fixed event propagation bug

Only webkit on touchscreen devices was affected.
model/tracking: Use smaller data types
xxx