Pyranges

Additions:
- pyranges_db now out on PyPI

Changes:
- PyRanges can now have Strand column with other data than "+" or "-", but it is considered unstranded.
- Ensure that slack parameter is always integer.
- no keep_metadata-flag in windows. Metadata is always kept. Can call drop() beforehand if metadata should not be kept.

Remove:
- remove confusing keep flag from drop method (use gr[cols_to_keep] instead)

Fixes:
- add missing ... in pyranges tostring

Removal:
- remove sandbox module

Additions:
- add insert method which uses overlap

Changes:
- read_bed does not fail when strand is "."
- read_bed considers bed unstranded if Strand has other values than +/-

Changes:
- tssify/tesify renamed five_end/three_end
- five_end/three end fails when data does not contain strand

Fixes:
- slack changed pyrange in-place

Fixes:
- assign changed pyrange in-place

Changes:
- minor bugfix