Version bumps

Add usage example and further unit test for new max option

Simplify max vs crop logic

Add details of performance test task - closes lovell#12

Minor markdown layout fix

Add support for auto-scaling of width and height

Expose vips internal cache settings and status

Add support for WebP and TIFF image formats. Closes lovell#7.

Take a temporary copy of buffers provided as input. Soak testing sugg…

…ests this prevents the problems seen in lovell#6.

Fix (unrelated) memory leak discovered whilst investigating lovell#6

Keep shrink-on-load logic DRY. Ensure canvas option (crop vs embed) i…

…s always as requested.