timers: fix timer regression involving redirects / reconnects

In commit 0b3750b5 (released in 7.36.0) we fixed a timeout issue
but instead broke the timings.

To fix this, I introduce a new timestamp to use for the timeouts and
restored the previous timestamp and timestamp position so that the old
timer functionality is restored.

In addition to that, that change also broke connection timeouts for when
more than one connect was used (as it would then count the total time
from the first connect and not for the most recent one). Now
Curl_timeleft() has been modified so that it checks against different
start times depending on which timeout it checks.

Test 1303 is updated accordingly.

Bug: http://curl.haxx.se/mail/lib-2014-05/0147.html
Reported-by: Ryan Braud