A button may only be mapped to a single action. Detect when the user
tried to map the same button to multiple actions and error out.
To clear a binding (for example, to free up a button from the default
bindings), one can set the action it is bound to to
`NONE` (e.g. `primary-paste=NONE`).
* New config section, "mouse-bindings", where bindings are defined on
the form "action=BTN_<name>
* pointer_button() handler now scans the bindings list instead of
hardcoding primary-paste to BTN_MIDDLE.
* The implementation handles single- double- and triple clicks in the
bindings, but there is currently no way to define anything but a
single-click binding in the configuration.
This adds parsing of a new section - "key-bindings" - where the user
can configure the key bindings on the form "action=combo1 .. comboN"
The validity of the key combinations are checked with the default XKB
keymap.
New actions defined and implemented:
* scrollback up/down
* font size up/down/reset
* spawn terminal
Break out key combo parsing to a new function,
parse_key_binding_for_action(). This function parses a string
containing one or more space separated key combo definitions on the
form (mod1+mod2+...+key), where key is a XKB key name (e.g. KP_Add).
Convert all hardcoded key bindings to configuration based
bindings. These still cannot actually be configured by the user, but
at least lives in the conf struct.
This adds initial support for defining key and mouse bindings that are
applied in different terminal modes/states.
For example, there are two arrays dealing with key and mouse bindings
in the "normal" mode. Most bindings will go here.
There's also an array for "search" mode. These bindings will be used
when the user has started a scrollback search.
In the future, there may be a model selection mode as well. Or maybe
"search" and "modal selection" will be combined into a single
"keyboard" mode. We'll see.
Since the keyboard bindings depend on the current XKB keymap,
translation from the user specified key combination string cannot be
done when loading the configuration, but must be done when we've
received a keymap from the wayland server.
We should explore if it's possible to load some kind of default keymap
just to be able to verify the validity of the key combination strings
at configuration load time, to be able to reject the configuration at
startup.
A couple of key bindings have been added as proof of concept.
Mouse bindings aren't handled at all yet, and is likely to be
re-written. For example, we can probably translate the configuration
strings at configuration load time.
