Toggle to select Flash or legacy uploader

[tellyworth]

This adds a link toggle to the upload page that allows the user to switch to the legacy HTML form uploader if they're having problems with the Flash uploader. (That happens automatically if Flash is not installed; the patch lets the user override the auto detection and force HTML even if they have Flash installed).

It could alternatively be implemented as a plugin, since it relies solely on actions and filters.

[ryan]

(In [8310]) Add flash uploader bypass toggle. Props tellyworth. fixes #7281

[DD32]

How does this fare for people using the no flash uploader? I have a feeling the plugin may completely override this.. If it was to hook in late (say 11), then it'll take priority over any plugins which modify it. (re-open if anyone feels like thats a good idea)

[DD32]

How does this fare for people using the no flash uploader?

By that i meant the no flash uploader plugins, eg ​http://wordpress.org/extend/plugins/no-flash-uploader/

[xknown]

add_query_arg sanitization

[xknown]

Sorry for the unrelated new patch, there was two little security problems in [8310] and I didn't want to open a new ticket.

[ryan]

(In [8312]) clean_url() for add_query_arg(). Props xnown. see #7281