Loading olm.lua as weechat script with `/script load olm.lua' causes
errors like this:
```
/nix/store/43jbh7yxh8j4gjfzbvpd9clncah5dip1-weechat-matrix-bridge-2018-05-29/lib/ffi.so: undefined symbol: lua_tointeger
```
As `olm.lua' is loaded by `matrix.lua' it doesn't need to be included
manually by the weechat configuration.
This aims to make the `weechat` package even more configurable. It
allows to specify scripts and commands using the `configure` function
inside a `weechat.override` expression.
The package can be configured like this:
```
with import <nixpkgs> { };
weechat.override {
plugins = { availablePlugins, ... }: {
plugins = builtins.attrValues availablePlugins;
init = ''
/set foo bar
/server add freenode chat.freenode.org
'';
scripts = [ "/path/to/script.py" ];
};
}
```
All commands are passed to `weechat --run-command "/set foo bar;/server ..."`.
The `plugins' attribute is not necessarily required anymore, if it's
sufficient to add `init' commands, the `plugins' will be
`builtins.attrValues availablePlugins' by default.
Additionally the result contains `weechat` and `weechat-headless`
(introduced in WeeChat 2.1) now.
