stbt control: Allow mapping Escape key
stbt control: Allow mapping Escape key

In the original release of `stbt control` mapping Escape key was not
supported because of a short delay between Escape character being
received and the remote control key being sent, which makes its use
somewhat inconvenient.

Nevertheless, some users still prefer to use this key in their keymaps,
despite the mentioned inconvenience.

wmanley/stb-tester,martynjarvis/stb-tester,wmanley/stb-tester,martynjarvis/stb-tester,stb-tester/stb-tester,LewisHaley/stb-tester,stb-tester/stb-tester,LewisHaley/stb-tester,martynjarvis/stb-tester,LewisHaley/stb-tester,LewisHaley/stb-tester,martynjarvis/stb-tester,wmanley/stb-tester,wmanley/stb-tester,LewisHaley/stb-tester,stb-tester/stb-tester,martynjarvis/stb-tester,martynjarvis/stb-tester,stb-tester/stb-tester,martynjarvis/stb-tester,LewisHaley/stb-tester,LewisHaley/stb-tester,wmanley/stb-tester