Fastscan: Only appear when there are suitable NIMs
FastScan: Give warning screen when no suitable NIMs are available

There was already a warning message screen available when there
was no sat tuner available now extend that to suitable tuners
and remove the disappear from menu as it was some kind of double
wise implemented during my previous commit
scan.cpp: Add missing fcntl.h include

Some compilers might complain like this:
error: 'O_RDONLY' was not declared in this scope
FastScan: Only search for suitable NIMs once
FastScan: Another small optimalization

When a recording is busy we do not need to search though NIMs
eDVBFrontend::readFrontendData: only get SNR/AGC/BER when we have a lock

avoids a few ioctl's while we're tuning
tstools: Correctly and efficiently calculate recording length

A recording with dicontinuities, such as when you've cut out commercials
or when there were big dropouts during recording, did not account for those
when the length was requested.

To fix this, take the discontinuities into account, which are calculated from
the .ap file. Use the "fixupPTS" function to correctly estimate the length.

Improve efficiency: Keep the calculated length as a member, because it is being
requested many times per second while playing.
frontend: Add SNR approximation in dB for MaxDigital XP1000 NIMs.

Thanks to theparasol for the percentage data. The approximation
might improve with more data.
no.po: translation updates by andy1
FastScan: follow nim_list --> nimList rename

in 19f4f7bf2f39c9662fc9bd9ab6aead26fada310e
Merge remote-tracking branch 'pli/master'

Conflicts:
	lib/python/Plugins/SystemPlugins/FastScan/plugin.py
	po/no.po