Can now clear tentative matches.

Doesn't actually achieve much, but allows you to remove mistakes
from the tentative list. (If they were proposed by the software, they
may be added again later)>
Put already known things in core ordered smallest first.
Fix bug in reading fifth element specification in chemkin thermo file.

It seems I was off by one in the column counting. Strange, as I thought 
I had triple-checked it!
Style formatting of code, by PyDev.

Normally it only updates lines you are editing, but for some reason
it has updated everything.
Enthalpy comparison is now done at 298K

This is less important to combustion/pyrolysis but perhaps more useful
for IDENTIFYING species (as opposed to comparing models).