Filter by more extensions/type in file manager

This edit allows to specify more than one value for fType and/or
fExtension.
bug http://www.concrete5.org/developers/bugs/5-6-0-2/asset-library-file-picker-doesnt-grab-post-value-in-attributes/
updated to use get and post only, not request
No sorting of list returned by event

One of the reasons the event could be used is to change the sort 
order. For example, to put local countries to the top of the list.
This change removes the asort from modified lists. Thus preserving
any specialised sort order.
No sorting of list returned by event

As with countries list. An event handler may have very good reasons
for returning a list with a specific sort order.
Fix locale during package upgrade

When installing a package, concrete5 forces en_US. Let's do the same
also when upgrading an already installed package.
Fix double-click paste error

When double-clicking on an item to paste it, the ui shows two pasted
items, but after a page refresh there's only one item pasted.
This fix avoid prevent double clicks.
Let's limit the page version comments length

Database field cvComments in table CollectionVersions is limited to 255
characters: let's avoid users inserting a value longer than that.
Fix page search index

This change fixes some troubles in the search index:
- converts &nbsp; to spaces
- converts some others html entities to text
Fix updating boolean attribute values

Let's accept boolean values when updating attribute values.

This allow setting to false boolean values.
explain next_previous settings better in edit.php
Show localized package info on install

Let's load the packages translations when showing the packages ready to
be installed, so that their names and descriptions are shown localized.
Ensure maximum length of last job status

The field jLastStatusText of the Jobs table and the field jlMessage of
the JobsLog table have a maximim length of 255 chars: let's ensure that
the saved value doesn't exceed this limit.
Ensure maximum length of last job status (no @)
Allow core package override by package handle string
fix next_prev block bug that showed excluded pages in some cases

fix bug in next_prev block where last page in section gets returned even if it has the "exclude_nav" attribute.
Retain prev/next classes on disabled pagination links

Removing the prev/next classes on their respective pagination links when they are disabled makes styling them difficult as they then have the same specificity as the numbered (page 1,2,3) links. It's easier in CSS to target .prev.disabled than just .disabled, because the latter requires extra work to target the desired link since other links in the pagination might also have the .disabled class.
Added numbers class to links in pagination

Allows easy differentiation in CSS/JS of numbered links from prev/next links
Add type check to Environment::overrideCoreByPackage
Remove Redundant Checks

Remove Redundant Checks as substr will return the same result as earlier
checks.