This check was fine earlier when we had access to the full filesystem,
but now that we are moving away from applications having unveiled
access to the filesystem, this check would just get rejected from
the kernel. This is rare / fast enough that performance should not
really matter in any case.
* Remove unnecessary #include statements
* Move it into the TextEditor namespace
* Mark the single-argument constructor explicit
* Use move() to avoid some unnecessary copies
This allows the user to specify a specific line and column number to
start at when opening a file in TextEditor through the terminal, by
adding a colon after the file name.
For example, `TextEditor ReadMe.md:10:5` will open ReadMe.md and put
the cursor on line 10 at column 5.
To ensure that the user isn't trying to open a file that actually has
colons in its name, it checks if the file exists before parsing.
Replaces the feature added in b474f49164Closes#5589
