Remove Beats::findNthBeat fuzzy behavior

[Holzhaus]

BeatmapTest.TestBpmAround fails for unknown reasons. Either the test is wrong, or our test coverage of the findNthBeat method is insufficient. I'll have to check later on.

EDIT: Works now.

I only removed two tests that explicitly tested this weird behavior. All other tests passed, so if this fuzzy behavior was indeed necessary for some feature, it should have been mentioned in a comment or required by a test case.

I suggest to merge this, unless we find major issues. Maybe we need it for beatjumps/looping, but in that case we should request snapping explicitly before called findNthBeat. I wrote a small convenience method that could be used for this.

[coveralls]

Pull Request Test Coverage Report for Build 1062636948

• 29 of 29 (100.0%) changed or added relevant lines in 2 files are covered.
• 795 unchanged lines in 15 files lost coverage.
• Overall coverage decreased (-0.03%) to 28.614%

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Files with Coverage Reduction	New Missed Lines	%
src/track/beatmap.h	1	60.0%
src/library/export/dlglibraryexport.cpp	2	1.29%
src/track/beatmap.cpp	4	76.97%
src/controllers/scripting/colormapperjsproxy.cpp	5	78.57%
src/engine/enginebuffer.cpp	15	86.22%
src/engine/sync/internalclock.cpp	20	80.51%
src/track/cue.cpp	20	65.56%
src/util/versionstore.cpp	23	1.3%
src/track/beatgrid.cpp	25	73.56%
src/engine/sync/enginesync.cpp	38	85.56%

Totals
Change from base Build 1022999157:	-0.03%
Covered Lines:	20084
Relevant Lines:	70189

---

💛 - Coveralls

[Holzhaus]

This resolves #3418 btw.

[ywwg]

This would not be the first time that some weird logic in Mixxx turned out to be totally useless.

[ywwg]

one small nit for clarity

[ywwg]

thanks!

[uklotzde]

Thank you! LGTM