Keybindings for selecting vector mesh elements

Graphite already supports selecting path points and segments and in the future is going to support vector meshes with enclosed cells (that also could be selected?). To my knowledge there is no standardization across 2D vector applications how to access path point/segment/cell selection mode. And as of now in Graphite we have this selector:

However dealing with different types of vector mesh elements is kind of standardized in 3D where we have vertex/edge/polygon selection modes that can be accessed with pressing respectively `1`, `2` and `3` on the keyboard in those applications:

Blender
Houdini
3DsMAX
Cinema4D
Modo

Personally after working for couple hours straight in Graphite I tried to hit 1 and 2 many times to switch between path point and segment out of habit and was surprised it didn't work. But I'm heavily biased because of my experience with 3D.

Moving all 3D arguments aside `1-2-3` are really close to `Tab` key that is already used for switching between object and path editing in Graphite, so in my opinion both would go very nice together.

Repérez les définitions existantes de Graphite pour path-point, segment, object-editing et les raccourcis clavier de Tab, puis examinez la façon dont le selector actuel change de mode. Définissez le comportement de 1/2/3 de manière cohérente avec le selector existant et vérifiez que les raccourcis permettent de changer entre les modes d’éléments disponibles sans entrer en conflit avec Tab ; prenez en charge la sélection de cellules lorsque ce mode existe.

Rédigé par le modèle d'indexation à partir du texte de l'issue.