Feat/calendar enhancement v2

[LenMPorath]

Solved Issues:

• 45 was fixed by using the already implemented methods for the Mensa Tile

• 46 was implemented in the Tile and Modal Day View.

• 47 was implemented similarily to the mensa tile. Same was implemented for the modal Day View

• 48 was implemented, Cases "Future", "Tomorrow", "Today", "Yesterday" and "Past" were covered.

• 61 Added Cache aging by checking if the pulled calendar is older than one hour. User can also manually fetch the calendar by pressing a new button at the top right of the Calendar Tile

• 77 Header of the EC was removed and implemented the removed functions into new prettier Buttons. same buttons and design from Day View were used for the Week view for more consistency in design.

Other features:

• Moved the Calendar Selector into the newly introduced Dashboard Tile Header (making it stick at the top above the tile content)

New Problems:

• 76 Switching between Tile and Modal sometimes leads to unpredictable behaviour of the calendar views. Navigation works fine tho. Needs to be fixed ASAP

[greybaron]

Initial state of calendar tile is handled incorrectly: no data is shown before switching once when localstorage is empty, likely the tile initializes at saturday

[greybaron]

The reload button doesn't affect the tile at all, it never refreshes