filter_blast: Simple BLAST-results filter
In robbueck/wisard: Perform wighted interval scheduling on a Genomic Ranges object

Filter BLAST-results by different criteria. Removes every alignment not fulfilling the criteria

1	filter_blast(raw_granges, min_len = 0, max_e = 100, min_identity = 0)

`raw_granges`	A GRangesList as returned from read_blast_xml.
`min_len, max_e, min_identity`	Integer or float to filter the BLAST-results by minimum length, maximum e-value or minimum percent idenity
`grange_output`	If set TRUE, output it a GRangesList object, otherwise a data.frame object.
`keep_sequences`	If FALSE, sequence and alignment columns are discarded.