Limner v0.8.1: Stability fixes and a cleaner install

Limner v0.8.1: Stability fixes and a cleaner install

This is a stability release. It fixes several editing bugs, hardens Limner
against damaged files, and tidies up how the app shows up in Windows, with no
changes to your files or to how any tool works. Illustration, Vector, and
Animation modes behave exactly as they did in 0.8.0.

Fixed

• Select ▸ Modify ▸ Expand, Contract, Border, and Feather opened nothing unless
  the Canvas Size dialog also happened to be open. The dialog now opens on its
  own.
• Panning could stick "on" if you held the space bar, switched away from Limner
  with Alt+Tab, then came back. Releasing space now always stops panning.
• Smudge and Blur could re-stamp a leftover smear onto a locked layer. A locked
  layer is now left untouched, including right after a stroke on an unlocked one.
• Pressing Enter partway through a free transform now bakes the result where you
  dragged it, instead of snapping back to the last committed position.
• Cutting with Ctrl+X, or re-picking the same tool, in the middle of a smudge
  now commits the smear cleanly with no leftover ghost.
• Opening a corrupt or malformed .limner, .artpaint, PSD, or brush file now
  fails safely instead of trying to reserve gigabytes of memory.

Improved

• A clearer Windows install entry. Add or Remove Programs (Apps & features)
  now lists Limner with its proper name and publisher, so it is easy to find and
  uninstall.

Notes

• Under the hood, a large amount of Limner's code was reorganized and tightened
  so future updates land faster. Behavior is unchanged, checked against the full
  test suite and an adversarial code review.
• No feature or file-format changes: documents save and load exactly as in 0.8.0,
  and every tool works the same.
• Windows, signed installer. Update from the in-app prompt or under the Help menu.