#43 Fix tests with Python 3

[Reinis Danne]

• Fix TabError: inconsistent use of tabs and spaces in indentation
• Fix string exception (SyntaxError: invalid syntax)
• Fix encoding/decoding of strings for buffered pipes in Popen (TypeError: Type str doesn't support the buffer API)

Some PyBel tests are outdated and one pytest_sym test fails:
55: Test command: /usr/bin/cmake "-P" "/home/reinis/Hack/OpenBabel/build_trunk/test/pytest_sym.cmake"
55: Test timeout computed to be: 1500
55: NOTFOUND
55: .....F..................
55: ======================================================================
55: FAIL: testXYZtoSMILESand3DMDL (main.TestConversions)
55: Test conversion from XYZ to SMILES and 3D MDL
55: ----------------------------------------------------------------------
55: Traceback (most recent call last):
55: File "/home/reinis/Hack/OpenBabel/openbabel/openbabel/trunk/test/testsym.py", line 248, in testXYZtoSMILESand3DMDL
55: self.assertEqual(canoutput.rstrip(), can)
55: AssertionError: 'I[CH][C]1CN1' != 'I/C=C/1\CN1'
55:
55: ----------------------------------------------------------------------
55: Ran 24 tests in 6.398s
55:
55: FAILED (failures=1)
55:
2/8 Test #55: pytest_sym .......................***Failed Error regular expression found in output. Regex=[FAIL] 6.45 sec

60: Test command: /usr/bin/cmake "-P" "/home/reinis/Hack/OpenBabel/build_trunk/test/pybindtest__pybel.cmake"
60: Test timeout computed to be: 1500
60: /home/reinis/Hack/OpenBabel/build_trunk/scripts/pybuild:/home/reinis/Hack/OpenBabel/build_trunk/lib
60: ........................==============================
60: *** Open Babel Warning in WriteMolecule
60: No 2D or 3D coordinates exist. Any stereochemical information will be lost. To generate 2D or 3D coordinates use --gen2D or --gen3d.
60: ..==============================
60: *** Open Babel Error in ReadMolecule
60: &)(%)($) contained a character '&' which is invalid in SMILES
60: ...==============================
60: *** Open Babel Error in SMARTSError
60: SMARTS Error:
60: [#NOEL][#NOEL]
60: ^
60:
60: ...==============================
60: *** Open Babel Error in ExtractUnitCell
60: CIF ERROR: missing a,b or c value - cannot interpret structure !
60: ==============================
60: *** Open Babel Warning in ExtractSpacegroup
60: CIF ERROR: missing spacegroup description: defaulting to P1...
60: .
60: ----------------------------------------------------------------------
60: Ran 33 tests in 0.593s
60:
60: OK
60:
7/8 Test #60: pybindtest__pybel ................**Failed Error regular expression found in output. Regex=[ERROR] 0.73 sec

[Reinis Danne]

Python test patch against trunk

[Noel O'Boyle]

Thanks. Applied in r4545.

I'm following up the test failures separately. One is already fixed.