The PHP Extension Release

A number of changes went in here.

• Pushed yum libraries upstream to ensure they are kept around for the future.
• Refactored the build system significantly.
• Added PHP build for Lambda against the same library as VIPS
• Added vips-php-ext build
• Updated documentation

libvips 8.5.5 for AWS Lambda

From the 8.5.5 Change Log:

• doc polishing
• more improvements for truncated PNG files, thanks juyunsang
• improve corrupted jpg handling, thanks juyunsang
• fix small test suite issues on os x

Initial build of libvips 8.5.4 for AWS Lambda

v1.0.0

Docker all the build things.