added sandbox/slice-reads-by-coverage.py
added collect-reads for streaming subsampling
Merge branch 'master' of github.com:ged-lab/khmer into feature/collect_reads
updated ChangeLog re collect-reads and slice-reads-by-coverage
added bigcount option to collect-reads
fixed docstring/help text in collect-reads
Merge branch 'master' of github.com:ged-lab/khmer into feature/collect_reads

Conflicts:
	ChangeLog
updated collect-reads to use running average, not average of last 1000, as per @mr-c
pylint fixes
catch exception raised by reads shorter than k
Merge branch 'master' of github.com:ged-lab/khmer into feature/collect_reads
Merge branch 'master' of github.com:ged-lab/khmer into feature/collect_reads

Conflicts:
	ChangeLog
whitespace/pep8 cleanup
Merge pull request #583 from ged-lab/feature/collect_reads

Tools for extracting reads by coverage