Fix #36451 : Alla breve forced to 2/2

Basically reverts commit https://github.com/musescore/musescore/commit/7ab8acd which was intended to fix issue http://musescore.org/en/node/14548 (apparently no longer needed)

Fix code is kept but commented out, with detailed comment and a small addition, in case the originanl issue pops up again in the future.

See http://musescore.org/en/node/36541 for more details, score samples and discussion.
fix #20122: [Linux] Export as pdf impossible, cannot determine file type
Comment removed.
Merge pull request #1384 from jpfleury/20122-export-pdf

fix #20122: [Linux] Export as pdf impossible, cannot determine file type
Merge pull request #1375 from mgavioli/Fix_36451_Alla_breve_forced_to_2_2

Fix #36451 : Alla breve forced to 2/2
fix some typos from PR #1385
Merge pull request #1394 from Jojo-Schmitz/capitalization

fix some typos from PR #1385
fix #37096: It is impossible to enter special characters from the F2 palette into lyrics