Mei export Updates

[manoskary]

This PR solves some relatively important issues that were overlooked with MEI export.

• Added important support for dotted notes.
• Added Cadence Class and visualization in the export.
• Added support for Beams in MusicXML which will nicely visualize and export beams in MEI.
• Added support for barlines, title and fermata
• Added a function to infer beams
• Updated rest infilling.
• Added support for cross-staff beaming.

Thank you.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 33.21678% with 191 lines in your changes are missing coverage. Please review.

Project coverage is 84.11%. Comparing base (018f264) to head (8de77aa).
Report is 1 commits behind head on develop.

Files	Patch %	Lines
partitura/score.py	10.00%	144 Missing ⚠️
partitura/io/exportmei.py	52.12%	45 Missing ⚠️
partitura/io/importmusicxml.py	96.55%	1 Missing ⚠️
partitura/utils/music.py	66.66%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #351      +/-   ##
===========================================
- Coverage    84.96%   84.11%   -0.86%     
===========================================
  Files           82       82              
  Lines        14236    14506     +270     
===========================================
+ Hits         12096    12202     +106     
- Misses        2140     2304     +164     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[fosfrancesco]

Adding functionalities for Cadence display, and correcting some problems in MEI export