Do not activate network on silentinstall

Closes #120 1.3 crashes with option "silentinstall"

(reason it crashes is actually that we are calling _qpd->hide()
when downloading the list of the Internet is complete, while _qpd
is not created on a silentinstall.
But no need for the network on a silent install anyway)
Disk space warning: account for 4 MB overhead per partition due to alignment
Treat data partition special

- If the item has "data partition" in it, do not allow it to be
  installed alone. Closes #103
- If the first partition is not a FAT partition, treat it as
  not bootable. Do not show it in the boot menu, and do not
  write config.txt to it. Closes #102
Translate [recommended] [installed]

- Closes # 126

(note that quite a few language.ts files are missing a translation for [INSTALLED] though)
Be more verbose in vncinstall mode

Users do not like black screens
Hide local image if newer network image is available

Closes #106