* fix extra newlines when copying from diff
See https://bugzilla.mozilla.org/show_bug.cgi?id=1273836
Basically, the <pre><code> seems to add a forced newline that is not
possible to get rid of via CSS, so I replaced it with just a <code>.
Secondly, .lines-type-marker also forced a newline in the copied text,
but that was possible to get rid of via user-select.
Safari still has a extraneous newline in the copied text of unknown
origin, but this should not block stop this PR.
* simplify .line-type-marker
* fix selector
* remove erronous ^^^
* Fix empty split diff
* Fix arc-theme-green
* fix add comment
* ensure line-num is copied too
* Update templates/repo/diff/box.tmpl
Co-Authored-By: zeripath <art27@cantab.net>
* attempt to fix safari via removing <code>
* remove useless whitespace at the end of 'class'
* remove inter-tag whitespace for code <td>s
* more inter-tag removal
* final inter-tag removal
* attempt to fix empty line copy
* move and comment getLineContent
* fix golint
* make background grey for missing added code
silverwind