local-metadata: Add tests for episode name parsing

This will allow us to fix old regular expressions, and add new
ones to detect season and episode numbers, without creating regressions.

https://bugzilla.gnome.org/show_bug.cgi?id=725026
build: Detect Lua in Debian systems

Debian packages lua pkgconfig file as lua5.2.pc, instead of plainly lua.pc.

https://bugzilla.gnome.org/show_bug.cgi?id=725299
lua-factory: Add grl.unescape() and grl.decode helpers

grl.decode will decode '%' encoded strings (usually URLs),
and grl.unescape will unescape HTML-escaped strings, usually
unicode or reserved characters.

https://bugzilla.gnome.org/show_bug.cgi?id=725381
lua-factory: Fix warnings when resolution fails

If the resolution fails, or the media passed from the callback
function is not in the right format, we need to pass back the
untouched original media, not NULL.
lua-factory: Factor out redundant code in lua_plugin_source_all_keys

The loop that gets the key names, checks if they exist, and adds
them to a list was repeated 3 times. Factor it out instead.
lua-factory: More warnings with unknown/unhandled metadata keys

Print out a warning when a key name is not registered, and upgrade
to a warning statement the debug output that warned about unhandled
GTypes.
lua-factory: Better warnings for unknown keys

So that script writers can see where the keys come from.
lua-factory: Fix "type" key in supported_keys

All those sources declared the "type" metadata key as supported,
but it's not actually a key. Remove it.

Also fix "mime" keys, it's actually called "mime-type".
filesystem: Bail out early for cancelled operations

https://bugzilla.gnome.org/show_bug.cgi?id=725203
radiofrance: Fix incorrect "mime" key

It's supposed to be "mime-type".
lua-factory: Don't warn for the "type" key

We don't handle it in this loop, but it's correct to define the
type of a GrlMedia and handled just above.
lua-factory: Add support for operation-id option

This is necessary to allow chaining calls while keeping state
between them using global variable.
lua-factory: Add cast conversion
pocket: initialize variables

https://bugzilla.gnome.org/show_bug.cgi?id=725425
all: Add names to all the timeouts and idles

For debugging purposes.

https://bugzilla.gnome.org/show_bug.cgi?id=725420
Updated Galician translations
Updated Hungarian translation
all: Use g_clear_pointer/object when possible

Reduces the number of lines and makes the code more readable.
Updated Latvian translation
all: Do not leak icon