Add a "delete all" or "clear layer" button in editing tool about lizmap-web-client

[mdouchin]

the sketch feature is interesting, but we shall not trust the user to manually delete his sketches after clicking on the print button. Better think of another way to achieve this feature (virtual layer in a virtual project)

[rldhont]

Does this feature can achieve this enhancement ?
issue #119
commit ade9bfb

[nboisteault]

@gioman Any remark to @rldhont suggestion ?

[gioman]

@gioman Any remark to @rldhont suggestion ?

in a way yes (but unless I'm missing something I can't see a "delete all" button/shortcut), and I still think that the idea for a real sketch feature/tool is valid.