2.7.4 --> 2.7.5
===============

Improvements:

- Adding items to a universe became significantly faster. This is most noticeable when opening a trajectory file for a big system.
- New example script NormalModes/conformational_change_analysis.py
- Added plotting to the example script NormalModes/calpha_modes.py
- New subcommand "test" for setup.py runs all the test cases and works before installation.
- The default visulization module was changed from VRML to VRML2.
- General cleanup of the code and the installation process. There are many fewer warnings now.
- Definition for He added to the database.

Bug fixes:
- NormalModes.effectiveMassAndForceConstant crashed due to a forgotten name change in a method call.
- Writing DCD trajectories could crash on 64-bit machines.
- Distance constraints were handled incorrectly in peptide chains connected by disulfide bridges.
- Universes using the SPCE forcefield could not be read back from a trajectory file.
- Creation of graphics representatios of Collection objects crashed.
- Interators and minimizers could hang if an error occured during trajectory output.
- Energy calculations on configurations containing NaN values crashed Python with a segment fault.