Enhancement: Integrate with dfmt to provide reformat command

[zhaopuming]

dfmt is a good tool to keep source code format clean and will become an official tool soon.

I noticed that currently dlangide lacks support for reformat code. So instead of reinventing this functionality I suggest just integrate with dfmt, in the same manner that you used dcd for autocompletion.

[buggins]

Do you know if it's possible to invoke DFMT to format only range of text (e.g. lines A .. B)?

[zhaopuming]

Looking at dfmt's code, you can just use dfmt as a library and call this function: https://github.com/Hackerpilot/dfmt/blob/master/src/dfmt/formatter.d#L17 with appropriate formatter config. It reads in a ubyte[] buffer.
I've not tried myself though.