Introduce fixed scaling custom setting

This addition allows for images to be displayed as (large) thumbnails
which all have the same size. I found this more pleasant than having an
image full-screen.
Merge remote-tracking branch 'upstream/master' into fixed-scaling

* upstream/master:
  Small fix for memecrunch url pattern
  Added support for quickmeme
Refactor inline rescaling to use one variable

erc-image-inline-rescale:
- nil     : no rescaling
- 'window : rescale, down only, to window size
- <number>: rescale so the height will be equal to <number>
Merge /home/mrb/.emacs.d/el-get/erc-image into fixed-scaling

* /home/mrb/.emacs.d/el-get/erc-image:
  Refactor inline rescaling to use one variable
Merge pull request #8 from mrvdb/fixed-scaling

Introduce fixed scaling custom setting