default insert size to 300 if zero
Merge pull request #33 from andrewjpage/default_insert_size

Default insert size
added sort contigs module
updated test
updated test
added sub first_read_length to FastqTools
In improve_assembly, remove contigs shorter than read length after gap filling
update outfile name
Merge pull request #35 from martinghunt/master

Filter contigs smaller thana read length
added sort contigs by length
fix merge conflict
added usage info
simplify output filename
simplified contig renumber
set final output filename
Merge pull request #36 from CraigPorter/order_contigs

Order contigs
fix for iterative abacas
updated delimiter sequence

 Changed delimiter sequence from 100 N to 100 N 100 G 100 N preventing
 erronious splitting of Abacs output sequence.
 Abacas fills gaps with Ns and indicates overlapping contigs with  a
 sequence of 100 Ns.
update test data for new delimiter sequence
Merge pull request #37 from CraigPorter/iterative_abacas

Iterative abacas