Implement sane behavior of space key in torrent content list. Closes #140.

Definitions:

Selection in QTreeView consist of two things:

   currentIndex -- is a (dotted) cell where user clicked last time. Note
                   that it is a cell
   selectedIndexes -- is a set of cells (blue) of current selection.

Checkboxes in torrent content lists are belong to COL_NAME column.

Problem:

The problem is that spacebar toggled checkbox only in currentIndex
index. This has two consequences:

  1. It is impossible to toggle checkboxes on multiple rows
     simultaneously.
  2. If currentIndex is not in COL_NAME column a space key doesn't work
     at all. This problem is amplifyed by the fact that SelectionBehavior
     is set to SelectRows. So visually it is impossible to tell which
     column does it belong to. For end user it looks like "space doesn't
     work sometimes".

This patch addresses the problem by implementing TorrentContentTreeView
derived from QTreeView and overridding keyPressEvent(QKeyEvent*).

The code of TorrentContentTreeView::keyPressEvent is written under
inspiration from QAbstractItemView::keyPressEvent and
QItemDelegate::editorEvent.
Vertical align right-aligned header text

Since e907306b411 ("Right align header text that also has right-aligned
row text"), right-aligned elements are no longer centered vertically.
This can be noticed with some Qt styles (e.g. Breeze).
searchengine: Update KickassTorrents url

Closes #2228.
Merge pull request #2229 from pmzqla/vertical-align

Vertical align right-aligned header text
Merge pull request #2230 from pmzqla/searchengine-kat

searchengine: Update KickassTorrents url
Fix compilation on ARM. Closes #2204.
Update Changelog.
Don't overwrite WebUI password when changing preferences

The input field to change password does not contain the actual
password, but its hash. When the preferences are saved, the hashed
password is considered as a new password.
Prevent this by comparing the new password with the hash of the
previous password.

Closes #2241.
Merge pull request #2242 from pmzqla/webui-password

Don't overwrite WebUI password when changing preferences
Merge pull request #1546 from Gelmir/add_paused

Partially revert 14310f9b0503d3dffa48bdb1bf9bdd5c754fa9d4
Implement peer relevance column. Closes #1630.
Rearreange header includes in Peerlist widget.
Add info about the proxy password being saved unencrypted. Closes #1490.
Fix for commit 35e964f66.
RSS Feed will format plain text descriptions
RSS Feed was not displaying remote images in html description. Closes #1119
Merge pull request #1122 from maxrd2/rss_html

RSS Feed was not displaying remote images in html description.
Merge pull request #1147 from maxrd2/rss_text

RSS Feed plain text description is not formatted.
Save RSS cache in folder called rss.
Follow project coding style. Issue #2192.