Revert "Revert Effects changes"

This reverts commit 12c7c4e70bedee327db53d54f4eba1858f6ecd6d.

The PR #22 is good now. Due to me messing up the commits really badly
the merge is done with reverts now.
fix markup error and wrong fact
add bitcrusher description
add reverb and filter
add echo effect docs
update filter effect description
Mention that reverb is not available in the app store version.
add versionadded information