Improvements in terminal #1

- Terminal moved permanently from plugins to components (this way the
plugin can be deactivated
- "Split" option removed as it had to be fixed to properly fit the
interface after the Terminal was implemented -> The code stills there,
it's just commented, can be fixed but requires time
- Basic Sandbox implemented in the Terminal, only the commands "ls",
"javac" and "java" are allowed
Improvements in Terminal #2

- Terminal moved permanently from plugins to components (this way the
plugin can be deactivated
- "Split" option removed as it had to be fixed to properly fit the
interface after the Terminal was implemented -> The code stills there,
it's just commented, can be fixed but requires time
- Basic Sandbox implemented in the Terminal, only the commands "ls",
"javac" and "java" are allowed