Remove typo from merge conflict
DOC: Use raw strings to avoid double backslashes in docstring math, as per PEP 257
DOC: Fix definition list formatting
DOC: Add missing type, fix list formatting
MAINT: Remove variables assigned to but never used
DOC: typo of 1/sqrt(2), tweak Bessel filter notes
Merge pull request #498 from endolith/merge_conflicts

MAINT: List formatting, typos, raw docstrings, and unused variables