This PR adds initial support to get and set the resolution of images for GD and Imagick, also it supports two resolutions units: ppi and ppcm (please see notes below).

Methods

• getResolution(): Resolution
• setResolution(\Intervention\Image\Resolution $resolution)
• setResolution(int $xy)
• setResolution(int $x, int $y)
• setResolution(int $xy, string $units)
• setResolution(int $x, int $y, string $units)

Notes

1. Tested on PHP 7.2, on 7.1 should work too, 7.0 (fixed and supported now) and below are officially dead and I don't see any reason to support them 😄 especially because the gd:imageresolution() was added in 7.2
2. GD supports only ppi, so setResolutions(ppcm) will automatically convert ppcm into ppi (imagick will use original units)
3. While processing images (and even after make()) GD will lose original resolution 😞 technically this can be fixed too but requires a lot of work and will not be included in this PR.