Remove external references to Conformer._E0

In rmgpy/statmech/conformer.pyx, _E0 is the private attribute backing
the public E0 property (to support an Energy cast on setting).
Respect that privacy and use the public interface.
Merge pull request #214 from wking/no-_E0

Remove external references to Conformer._E0

In rmgpy/statmech/conformer.pyx, _E0 is the private attribute backing the
public E0 property (to support an Energy cast on setting). Respect that
privacy and use the public interface.
Updating tunneling to allow calculations for symmetric Eckart

Allowing for symmetric eckart tunneling. In symmetric eckart
we assume the reactants and product have the same energy, therefore
the terms
dV1 = E0_TS - E0_reac
dV2 = E0_TS - E0_prod

will be equal. To allow for this I have relaxed the assertion
dV1 < dV2 to dV1 <= dV2.

It works fine for my test reactions. I would assume the assertion
was originally placed anticipating so as not to run into
a numerical issue (division by 0).
Merge pull request #222 from shamelmerchant/master

Updating tunneling to allow calculations for symmetric Eckart
Add more features to checkWellFormed in family.py

Add bit of code to identify products better. I check the name of groups I
think are products vs the products listed in forwardTemplate.products.

One error we check for is if a label in rules.py is misnamed, i.e. if any
part of the label is not a group in group.py. There a decent amount of
these errors due to the recent Java/Py database merge. To make my life
database debugging life easier, I added a new feature which tells me if
there is a group which matches the misnamed label.

For example, let's say we have a rule label, A;B. Somebody changed the
name of A to C in groups.py, but left it unchanged in rules.py. The new
feature would suggest C as the correct name for A, by comparing adj lists
of the rule and those in groups.py

Unfortunately, there is a bug I can't figure out. If somebody changed A to
C
AND B to D, it suggest C for A and C for B. The manual work around
is to visually verify which one adjList C matches, make the fix, and run
checkWellFormed again. It will then suggest D for B. I feel like this
isn't worth fixing because it will be unable to suggest groups with the
upgrade to universal database (once all adjlists are removed from
rules.py)
Reworked the checkWellFormed in KineticsFamily for testing database.

The identifying of node names and labels based on the actual nodes 
is different.
First, we check if it's right, i.e. if the groups named in 
the label 'group1;group2;group3' are indeed the same groups in 
the groups.py file.

Then, if not, we try to figure out what it should be called.
For each group in the actual node, we look through the groups.py
file to see if we can find one, and if so suggest that name.

I think this logic flow works better than what was there before,
but I did change/break the way it reports errors. Previously it would
collect them in a list of tuples, then return a tuple of lists, and
whatever function had called it (eg. in EvaluateKinetics.py in the RMG-database
project) would have to deduce what this meant and report the errors.
That means keeping the two files, in different projects, in sync
as the tuple/list syntax changes.  Rather than figure this out, I 
just report the errors as they are detected. If you prefer the other,
mute my logging lines, and compile a tuple as before.

Hope this helps.
Improve error reporting in checkWellFormed

1) Less code duplication by grouping the if statements 'if not (a and b):'
2) Report what the group definition should be if the label were correct
   (this could be helpful if the label was right but the groups out of date)
Add databaseTester.py script for testing database

Previously, I had to develop back and forth between the RMG-Py and
RMG-database every time I wanted to make a change to checkWellFormed. Now
I have moved it so it is entirely in RMG-Py.

The format which I report errors has also changed. At the moment, some errors
are returned as tuples, parsed and recorded into a file called
DatabaseWellFormedSummary.txt. Some of the other errors are reported using the
logging library. I plan on unifying how this is done in subsequent
commits.
Changed output format for databaseTest

Now all the errors that are searched for print to a database.log instead
of the hardcoded output file I had previously.
Fix parsing error for products in database checking

When the database is formed, it also creates groups for the products,
which would not be found in groups.py. These were usually labeled as
'product' + an integer. I ran into comparison issues with names with
parenthesis. I have revised the regex I used with re.escape, so that I
don't get these false positives anymore.
Find database path from settings when running databaseTester script.
When checking database, print out adjlists and logicOR groups
rather than RMG objects for debugging.
The beginnings of reformulating the database tests into working unittests.
Store the children of product groups when they are generated by RMG.

Product groups not found in the reaction family are automatically generated
by RMG for finding reverse reactions.  These groups don't have tracking
of parents and children like the rest of the groups.

Introduce this new functionality to track the children and parents
of the introduced groups.  i.e.

LogicOR Y
  - Group Y1
  - Group Y2
  - Group Y3

This way database testing can be done methodically.
Unittest for checking whether groups are found in tree now working.
Fix incorrect error msg in rmgpy.molecule findSubgraphIsomophisms function.
Add more detailed docstring to matchNodeToStructure function.
Define function matchNodeToNode for checking if groups are identical.

Currently can only check Groups against Groups and LogicOrs against LogicOrs
and assumes that everything else is false (which might not be the case, but it's
much harder checking that.)
A set of unittests for the matchNodeToStructure and matchNodeToNode functions
Added unittest for checking if groups are nonidentical in databaseTest