v0.5.3

Imagor 0.5 onwards revamp file I/O and leverages vips_thumbnail_buffer and vips_thumbnail where possible and using native file sniffing from libvips. These improve I/O performance, especially for file loader and storage.

• feat(vips) revamp vips thumbnail construction to support both file and buffer
• feat(vips) added option -vips-max-width -vips-max-height
• fix(imagor) fix nil pointer dereference on empty response cases
• feat(vips) add option -vips-load-from-file