add filter for category

[infinitel8p]

add a filter to select the spot category you want to see on the map

[infinitel8p]

• added dummy filter menu in MDToolbar
• added filterpopupmenu.py which currently is just a copy of searchpopupmenu.py
• added the class FilterPopupMenu() which is the dummy from filterpopupmenu.py to the main.py to have a working button in the MDToolbar
• added filterarguments.py which contains a array which will be used for the arguments to filter after
• added a if statement in topspotmap.py to skip the creation of markers whose category is listed in filterarguments.py

Changes are in Commit 7a1d029

[infinitel8p]

• create a working FilterPopupMenu() which changes the Array in filterarguments.py
• figure out a optimized way of removing and skipping marker creation according to the filter arguments