pidgin/pidgin

Add icon-name, icon-search-path, and icon-resource-path to PurpleProtocol

These are now used by pidgin_create_icon_from_protocol which will attempt to
load the icon for the protocol from the default GtkIconTheme if the protocol
has a non NULL value for icon-name.

pidgin_ui_init was also updated to add icon-search-path and icon-resource-path
to the default GtkIconTheme when a protocol is registered. It also scans all of
the protocols that have been already been registered as that happens before the
ui is initialized.

Testing Done:
Removed old local icon and then ran with an inverted icon to make sure pidgin was displaying the icon from the resource.

Reviewed at https://reviews.imfreedom.org/r/790/
# Purple, Pidgin and Finch
libpurple is a library intended to be used by programmers seeking to write an
IM client that connects to many IM networks. It comes with support for Bonjour,
IRC, and XMPP, among others and there are many more networks supported via
[third party plugins](https://pidgin.im/plugins/).
Pidgin is a graphical IM client written in C, which uses the GTK toolkit.
Finch is a text-based IM client written in C, which uses
[libgnt](https://keep.imfreedom.org/libgnt/libgnt).
These programs are not endorsed by, nor affiliated with, any proprietary
instant messaging company in any way.
## Contributors
See AUTHORS and COPYRIGHT for the list of contributors.
## Building
Pidgin uses [Meson](https://mesonbuild.com) as its build system. There is a
long list of dependencies that is not currently documented here due to
differences in package names across operating systems. We plan to fix this
soon, if you have any suggestions on how to handle this, please let us know.
You can quickly build Pidgin with the following commands:
```
meson build
cd build
ninja
ninja install
```
There are quite a few options for the build that you can view by running
`meson configure` in your build directory. You can specify the options when
running meson like the following:
```
meson -Ddebug=true build
```
If you have already run `meson` you can use `meson configure`:
```
cd build
meson configure -Ddebug=true
```
## Running
Currently Pidgin can not be run from a build directory, which means you must
install it first. Once you've done that, you only need to run `pidgin3` or
`finch3`. If it fails to launch you may need to run `ldconfig` as root.
To get started, simply add a new account.
If you come across a bug, please report it at:
[issues.imfreedom.org/issues/PIDGIN](https://issues.imfreedom.org/issues/PIDGIN)
## Plugins
libpurple, Pidgin, and Finch ship with a number of plugins, but you can find
additional third party plugins at
[pidgin.im/plugins](https://pidgin.im/plugins).
## Developing
You can find more information about Pidgin development in the
[development section](https://pidgin.im/development/) of our website.