Add program for generating tone periods

This tables are used in `BKTrack` to calculate the wave period for notes and
samples.
Add sample period calculation function
Implement sample speed control with notes
Add sample example
Add english note `B` as valid note name

`B` and `H` now name the same note.
Replace note `H` with `B`
Add new example file
Remove whitespace and unused comments
Add new test raw file
Add entry in ChangeLog
Reset sample when setting new note

Sample can now be played once if `BK_SAMPLE_REPEAT` is 0 or repeated as long as
the note is on (`BK_SAMPLE_REPEAT` is 1).
Update sample
Add check if wave is changed

Do not reset phase if waveform is the same as before
Update ChangeLog
Add tremolo to reduce bass a bit
Do not mute note when setting new instrument

When changing the instrument while a note is playing the attack sequence of the
instrument is played again.
Cleanup sample
Cleanup whitespace
Resample to 44100Hz
Add end command