MUS-107 bpm

Changed fixed bpm to variable bpm
MUS-107 NoteLength -> Milliseconds and vice versa

Added functions to
- get a NoteLength object from milliseconds
- get milliseconds from a NoteLength object
MUS-107 Finished TickProvider

A user can now play variable length notes
MUS-107 Filled Notes

Drawing: Added logic to distinguish between filled and unfilled
NoteSymbols
MUS-107 Added dotted NoteSymbols

Added draw function for dotted NoteSymbols
MUS-107 Test Case refactoring

Changed a MidiPlayer get method to make tests more readable
MUS-107 Added NoteFlag

- AbstractDrawerTest: added assert on teardown
- Added enum NoteFlag (no flag, single flag, double flag)
- Refactored NoteLength (added getFlag)
- Added missing NoteSymbol tests
- Deleted a PianoActivityUiTest. It is broken because of the variable
note length change, but this feature will be gone in an upcoming Jira
issue anyway
- Added NoteFlagDrawer
MUS-107 Fixed bpm bug

Fixed a bpm bug in the converter class
MUS-104_TrackTimeLength

Added a method to the track class to get the total track time in
milliseconds
MUS-108 Added Project copy constructor
MUS-108 Added missing tests (symbol package)
MUS-108 Added break drawer

- Added break drawer
-Renamed NoteDotDrawer into SymbolDotDrawer
- Added break images
MUS-108 Deleted NoteDotDrawerTest

Renamed into SymbolDotDrawerTest
MUS-108 Added BreakDrawerTest

- added tests
- added a feature in the tickprovider to add breaks through the
instrument
MUS-108 Tests refactoring

- Added drawer mock classes to make tests more readable
MUS-108 Break Images

The break images now share the same width (reduced file size of
break_16.png and break_8.png)
MUS-120 SymbolsToTrackConverter

- Renamed NoteEventListToSymbolConverter
- Added SymbolsToTrackConverter