add setDirectory function

[dj1vs]

setDirectory function opens terminal in a specified folder (just a cd command)

[ChargeIn]

Hey, thanks for the pull request, its good idea.

Since there is currently terminal does not have a setStartDirectory function most people will probably use this command to change the default directory the terminal is started in. This is a bit problematic, since the terminal takes some time to start and causes the command to generate duplicate entries on start up.

Furthermore we cannot simply call commands like "clear" afterwards since some terminals provide start up information.

So we would need to solve this first.

Also please move the function below the signal function e.g. the updateTerminal function.