The name was a relict from the very first day of project structuring,
but this name here makes for much much nicer tab-completing to source
file names...

Files opened from the filesystem are now read only and not marked as
"modified". A tooltip listing the major shortcuts has been added. The
regex for coordinates has been improved (it is now the same as at the
other places in Inishell).

Otherwise, re-ordering of the variables declaration for better
alignment.