(Bug 4819) Reset width/height to auto to override HTML attribute

Reset the width/height to auto first before applying a max-width/height.
This is to fix distortion of non-square images (where one dimension >
75px)
Merge pull request #201 from afuna/contextual-nonsquare-bug4819

(Bug 4819) Reset width/height to auto to override HTML attribute
(Bug 4818) Add groups and xpost metadata to Entry::print_metadata
Merge pull request #202 from afuna/xpost-links-bug4818

(Bug 4818) Add groups and xpost metadata to Entry::print_metadata
(Bug 4821) Only handle left-click for tracking new entries

We're not interested in right-click or middle-click.
Merge pull request #203 from afuna/middle-click-bug4821

(Bug 4821) Only handle left-click for tracking new entries
Merge branch 'release-1.13' into develop

* release-1.13:
  (Bug 4821) Only handle left-click for tracking new entries
  (Bug 4818) Add groups and xpost metadata to Entry::print_metadata
  (Bug 4819) Reset width/height to auto to override HTML attribute