Integrate oasis-align-images logic into oasis-align

[jdpieck]

oasis-align-images uses an equation to find the ideal fraction for two pieces of content with fixed aspect ratios. This means that content can be perfectly aligned, while oasis-align is only able to get a solution within tolerance.

By starting the oasis-align parameter fraction at the point calculated using oasis-align-images, fixed aspect ratio content will automatically be aligned while still allowing for other kinds of content to be aligned.

(Thanks to @Aaron-Rumpler for the suggestion!)