command hotkeys should be escaped instead of executed

[alodahl]

cmd+t
cmd+n
cmd+shift+esc
cmd+space
cmd+tab
cmd+shift+~
cmd+shift+3

hotkeys should be escaped. Right now they are executed and interfere with the program.

potential solutions have been discussed in issue #32

Update: This was partially addressed in #118 , with these exceptions:

"Fixed for some key combinations; could not overwrite in Safari for command + n, command + m, command + t, command + w. I also tested in Chrome and at least command + n was still not working. Seems like it might be a browser issue with not allowing me to catch those events and override them. In my research I came across this library which may be able to help: https://craig.is/killing/mice."

[KatShambaugh]

I will look into fixing this!

[KatShambaugh]

I have fixed this for a few of the command + key combinations, though some of them it seems like the browser won't let me override the keyboard shortcut.

[alodahl]

#118 addresses, but doesnt resolve this issue. Move it back to 'To do' once #118 is merged.