Abort unfinished XHR requests when calling reloadList

Previously, clicking e.g. "unread" and then clicking "newest"
before the first request had finished and while the spinner
was still visible, the page would first show unread items
and a second later show the newest items instead.

Also, the "Load list error" alert is now only shown when
errorThrown isn't empty. Previously, the alert would be shown every
time the user refreshes the page while there's still an XHR running.
Abort unfinished XHR when going to/returning from sources
Destroy spectrum before removing colorpicker divs

Previously, every time refreshTags was called, sp-container divs
were being left behind. We need to clean those up before removing
the divs that spectrum was initialized with.
Typos in french localization
Don't refresh items twice after returning from sources

This change triggers the onhashchange handler without sending
the reloadList ajax request, instead of triggering it only after the
request has been made and the items have already just been refreshed.
Clean up orphaned items (fixes #291)

Extends the cleanup function of the items daos to remove any items
whose source field doesn't have a corresponding entry in the sources
table.

The argument is now optional, so if cleanup is called without
arguments, it will only remove orphaned items from the database.
Behaviour of cleanup when called with an argument remains unchanged.
Decode HTML entities before passing to htmLawed

Some websites encode the title or content of their feeds with HTML
entities (for example the Wired feed). HtmLawed doesn't recognize
tags that are already entity encoded, so we have to decode them first
in order for htmLawed to neutralize/remove all tags correctly.
Merge pull request #293 from seanrand/fix-entities-html-tags

Decode HTML entities before passing title or content to htmLawed
Merge pull request #292 from seanrand/orphaned-items-fix

Clean up orphaned items (fixes #291)
Merge pull request #289 from gapato/patch-1

Typos in french localization
Merge pull request #288 from seanrand/spectrum-reinit-fix

Don't leave behind sp-container divs when refreshing the tags
Merge pull request #286 from jicho/master

New shortcuts + "new title" placed in placeholder
Merge pull request #287 from seanrand/reloadList-fix

Fix issues with refreshing the items list and slow ajax requests
Update cn.ini
Update tw.ini
Merge pull request #297 from PowerIVQ/master

Translation
readme update and small design improvement
remove html decode in ContentLoader.php
Merge branch 'master' of github.com:SSilence/selfoss
Decode HTML entities before passing title or content to htmLawed (#293)