gitignore improvements
move naming from mesh->asset
add image mode to camera
meshSource -> assetSource
alignment with up vector
first work on ortho camera
Images now loaded with correct units and size
thumbnail support
proof of concept for PIP
auto setting of image mode (needs work)
Merge branch 'image' into ortho
3 separate cameras, ortho, per, othozoom
Merge branch 'pip' into othopip
PIP enabled and tracking mouse
fix for selection methods, target on pip
closes #30
closes #27, #31, 35
formalised asset vs mesh

asset is either an image or mesh. it has the correct id set and can be
inspected to find any metadata. Mesh is always a mesh class. It is
guaranteed to be set after asset on app.
closes #36
j/k next/previous asset.