Compare whole genome size

[eweitz]

This implements features needed for comparing the length of whole genomes:

• Parallel collinear genomes
• Chromosome scaling

Parallel collinear genomes are two lines of chromosomes. Each line is the genome of an organism.

Chromosome scaling can focus comparisons on either genome size or chromosome structure.

By default, a relative scale is used for chromosome length. It equalizes the pixel length of the first chromosome in each genome, then from that reference scales subsequent chromosomes in each genome. It smooths differences in total genome length. This allows easier comparison of structure within chromosomes (e.g. centromere position) at the cost of less accurate comparisons of genome size (i.e. genome length).

An absolute scale is also available. This makes it difficult to compare structure within chromosomes between two genomes, but allows more accurate comparison of genome size.

The example below compares genomes of human and the plant Arabidopsis thaliana.

[coveralls]

Coverage decreased (-0.3%) to 90.532% when pulling 39869fb on compare-whole-genomes into be768fb on master.