Add apply button to settings dialog.
Merge pull request #96 from Kapeli/master

Add Markdown icon
Add requirements section in README
Merge pull request #98 from webmaster128/master

Add requirements section in README
Added information about bsdtar to the README
Merge branch 'master' into applySettings.
Merge pull request #99 from MichaelBeeu/applySettings

Apply settings
Fix QString argument substitution

QString replaces only %1,%2 with arguments.
Add warning if bsdtar is absent

If zeal cannot launch bsdtar it loops total download progress bar
endlessly, which looks like it hangs. User must be warned if something
goes wrong, so I added QMessageBox to say about this.

Also, 'program' variable not changed anywhere and can be declared as
constant.
More helpful message about bsdtar missing
Handle GitHub 302 redirects (fixes #102)

 - http://bourbon.io/docset/bourbon.tgz was redirecting to /docset/bourbon.tgz
Show tooltip for external URLs (#82)
Merge pull request #108 from MichaelBeeu/linktooltips

Show tooltip for external URLs (#82)
Find previous with shift+enter (#73)
Moved tooltip code to a little more sensible location.
Merge branch 'master' into findBack
Merge branch 'linktooltips' into findBack
Merge pull request #109 from MichaelBeeu/findBack

Find back
Adds title for any viewed page.

The title displays the icon of the current docset as well as the end of the url path.
This allows to quickly view the name of the current module/function.
Fixes clearing of the search box.

If the search box is cleared and then a query is completed the treeView does not get populated with search results