Improving shell support; adding parse of options.

1. Add warning; CFFS file size is restricted to one sector (64Kbyte).
Directory entries are not compacted.
2. Add command action support; new member function to allow parse of options.
3. Update example sketch; CosaCFFSshell.
Reduce program memory requirement for string; reuse command name in help.
Adding an additional Shell example sketch. Adding scripting.

1. Improving Shell; adding echo of command line and scripting i.e. allow
command lines from program memory.
2. New example sketch with basic Arduino language as commands.
Fixed checking of index limits.
Inital checkin.

- This code works but needs more work.
BUGS:
- The plan is to be able to have the displays in a X*Y formation where X
  and Y can be anything. It should currently only be possible to use one
  line of displays with arbitrary amount of displays, but I've only
  tested with one and two displays.