add fast HEIC support

[catdad]

see #278 and #281

[catdad]

ImageMagick can convert heif relatively quickly (~1.5s), but I would want to have static builds for Linux/Mac (I can only find ones for Windows currently):

PS D:\Workspace\Photography\heif> Measure-Command { ./magick.exe IMG_4453.HEIC test.jpg }

Days              : 0
Hours             : 0
Minutes           : 0
Seconds           : 1
Milliseconds      : 521
Ticks             : 15217412
TotalDays         : 1.76127453703704E-05
TotalHours        : 0.000422705888888889
TotalMinutes      : 0.0253623533333333
TotalSeconds      : 1.5217412
TotalMilliseconds : 1521.7412

[catdad]

tifig works well and only ~500ms, but are builds only available for Linux?

kiril@whitson:/mnt/d/Workspace/Photography/heif$ time ./tifig -p IMG_4453.HEIC test.jpg

real    0m0.484s
user    0m0.453s
sys     0m0.016s

[catdad]

sharp can also handle HEIC, but requires a special version of libvips and I have not tested it.

[catdad]

Nokia has a reader and writer, but I have not looked into them: https://github.com/nokiatech/heif