custom compiler context for remix-tests CLI

Adds an optimize flag to the commander CLI config which generates a
CompilerConfiguration object and passes it down the line to the
compiler optionally.

The file removed event will not be emitted if the file is deleted when it is not opened. This happens for example when you right click on the file without first openening it.

I've added an option so that plugins can activate other plugins by adding an extra optional line to the profiles
canActivate: ['plugin1', 'plugin2', ... ]
This will allow that plugin to activate other plugins. But we can curate this when the profiles are made.
This optional. If the other plugin does not exist or the caller doesn't have canActivate in its profile it gets caught.

FE user selection

fix #588

File explorer