Better error message when unable to determine atom type.

The new error message will now also show the number of each type of bond
that it identified, which is the key means of determining the atom type
besides the element.
Fixed another bug in reading of G3 energies from Gaussian log files.

"0 K", not "O K"
Log memory use at end of standalone CanTherm job.
Temporary work-around to read broken cantherm input files (see issue #112)
Added linebreaks in some long method declarations.
Split chemkin.loadChemkinFile into smaller functions.

I have made a readSpeciesBlock and readThermoBlock just like
the existing readReactionsBlock.
This is so you can call them independently, should you need to.
Add pickling functions to PDepNetwork class.

Not entirely sure these are necessary, but I think they're an improvement.
(The bug I'm chasing in #117 has either gone or moved).
Chemkin thermo parser reads more detailed info.

It now extracts the comment, checks the phase, and extracts
the chemical formula.

* readThermoEntry returns (name, thermo, formula) whereas before
it was just (name, thermo).
* readThermoBlock now returns a dictionary of formulae, whereas
before it didn't return anything.

The formula is a dictionary of (element: number) pairs, like
{'C':2, 'H':6}
Fix bug reading chemkin reactions.

If a line had 'rev' in it, the next line was read, but the comment processing
was not done to it, so if you had a line with REV followed by
a line that begins "  !! comment" then it would die.
Deal with explicit reverse reactions differently when reading chemkin files.

Instead of just skipping any line containing REV we now attempt to read it.
We store the explicit rate in a comment on the kinetics, and if it
is zero, we make the reaction irreversible. We do not create explicit reverse
reactions (just store the comment).
I expect it will not work for PDep or Duplicate reactions, only plain vanilla
high-P Arrhenius rates.
Import the *other* Species class in rmgpy/chemkin.py

In the checkin importing script I need the rmg-specific Species,
not the general Species.
Chemkin reader preserves case of species labels.

Previously it turned them all into uppercase.
Merge branch 'chemkin'
Tweak error message to help debugging.

Also tweak a docstring.