Fix output format of optional BED fields
Undo format change for unstranded cases
Add new stranded test cases
[DOC] typo
Update merge.rst

Change "separated by commas" to "separated by semicolons"; semicolons are the default delimiter.
Merge pull request #91 from ecwooten/patch-1

Update merge.rst
Merge pull request #89 from kcha/merge-patch

Fix output format of optional BED fields
point to bedtools2 repo.
Update installation.rst
Merge pull request #97 from arjanvandervelde/patch-1

Update installation.rst
Update cluster.rst
Merge pull request #98 from rchikhi/patch-1

Update cluster.rst
Title correction on -counts part
Merge pull request #99 from Guitss/patch-1

Title correction on -counts part
Update README.rst