OP-1576: Remove unused tx_resent counter

Remove unused tx_resent counter and replace it with
rx_failure in link quality calculations.
OP-1522: Channel timeout logic

Use real time rather than missed pickets when deciding if we are
disconneted. Makes the link less sensitive at higher rates since
higher rates means more chances to get a packet through within the
given time.
OP-1522 New channel allocation

Generate a pseudo list of random channels from hmac_sha1 with the
coordid as key.

Enforce channel spacing based on the frequency deviation derived the
configured data rate.
OP-1576 Removed TxResent from GUI. Renamed some files.
OPLINK-1522: coordid must be set befor chan init