Implement execution of commands

[X547]

Pe support execution of shell command by selection text and pressing Alt+Enter or check icon on tool bar. It is very useful by preparing a list of commands and invoking it instead of typing it every time in Terminal. Also unlike Terminal, Koder supports regular text editing like common shortcuts and setting caret position by mouse.

Also please consider HaikuArchives/Pe#64.

[X547]

It will be also nice to have ability to execute commands with middle click like in Oberon.

[ttcoder]

I too use a worksheet with Pe.

BTW when that feature is implemented, what about including an stderr parsed listing (GCC error messages clickable list) like Pe does.
Haiku's Terminal is great for that kind of thing, with file paths/line numbers being clickable, but there is still merit to a Pe-like list that gets out of the way, colors warnings in yellow and errors in red etc. (EDIT: oops I see that this is already mentionned, at the end of OP message)

@X547 :

It will be also nice to have ability to execute commands with middle click like in Oberon.

Wouldn't that conflict with middleclick-for-function-list feature, needed for Pe parity? :-) #28 (or maybe let's make this -- also -- configurable, so that clicks can be a different preference for different people..?)

BTW hello Kapix and Koder users. With the switch to Haiku R1/beta2 I started looking into Koder, at long last.