Move zooming support from webgl canvSize hack to the vertex shaders

An important side-effect is that zooming happens to the center of the image.
webgl: Adjust canvas height to keep texture's aspect ratio
Lightfield grid: Rescale by image size, not canvas size
Lightfield grid: Do not wrap the X coordinates needlessly
Lightfield grid: Make setting persist by storing selection in showGrid session variable
Lightfield grid: Add support for UV-based grid shift
Replaced db dump and updated documentation
Minor formatting fixes
Updated db dump and readme
Merge branch 'master' of https://github.com/nemaload/nemashow
More README formatting fixes
Lightfield: Add support for dragging the (potentially magnified) source image - useful for examining grid alignment
Merge branch 'master' of github.com:nemaload/nemashow
Merge branch 'master' into production

Conflicts:
	README.md