jimtcl: New package

Add new jimtcl package - a lightweight tclsh alternative.
Useful for a lighter footprint usb_modeswitch installation.
tclsh size is ~700kB for ARM compared to ~200kB for jimtcl.

[Peter: wrap help text, fix file header]
Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Ezequiel Garcia <elezegarcia@gmail.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>