[Feature Request] add %SELECTION% variable

[sepisoad]

this can allow focus to pass current selection to commands, for example

[Run]
run_command:            echo %SELECTION%

i can see this can be an issue when multiple cursors are active and there are more than one selection, maybe in such cases the selection can be ignored/left empty

adding %SELECTION% variable opens the door to many opportunities, you can pass the whole buffer or part of it to 3rd party tools.

however there is a catch here, maybe this feature would be useful only if the result of the command can be replaced with selected text which in this case it might not be a good candidate for a command variable, maybe a pipe_command accompanied with %SELECTION% can make more sense:

[Run]
pipe_command:            epoch2date.sh %SELECTION%

p.s. i know pipe_command does not exist