Unicycler v0.4.5

Changes in this release:

• Improved checking for dependencies when installing (thanks @kblin!)
• New option --min_anchor_seg_len to explicitly set the minimum length for scaffolding anchors
• New option --kmers to explicitly set SPAdes assembly k-mer sizes
• New option --spades_tmp_dir to specify a location for SPAdes' temporary directory (solves #69 and #82, thanks @rec3141!)
• Tweaks to logic which determine chromosomal depth - improves performance on some contaminated read sets