Rework PSD plugin.
Review Request #122654 - Created Feb. 20, 2015 and updated
It now theoretically supports reading almost all PSD and PSB files, with the major exception of ones with 32-bit-per-channel colour. However, the code is almost entirely untested, due to me not having access to Photoshop.
As a result this is semi-speculative (I could commit it and hope for bug reports, but I'd rather test it properly).
Not enough (although the existing unit test passes).