[configs/alter] December update

* Remove package:
  * deadbeef-mpris-plugin - doesn't work fine any more
* Add package:
  * mosh
  * indent - formatting C code
  * splint - enhanced lint: check the code mistakes in C code
  * some legacy xorg apps like twm and so on
  * rdesktop - client for Windows Remote Desktop Services
  * sslstrip - hijack HTTPS connections during MITM attack
* Update the Offline installation guide
* zshrc: remove memsizestat(), as the new procps-ng(3.3.10-1) provides 'free' command could display the 'available' column now