GitLab

* add tests for correctness of step and time written in XTC and DCD

* improve tests

* improve xtc tests

* fix XTC/DCD time/step writing

* different approach by changing the reporters to not pass currentStep as firstStep but instead interval

* undo change

* Can use getPlatform() instead of getPlatformByName()

* More concise arguments for getState()

* Top level Python module is now "openmm"

* Updated module names in examples

* Updated module names in documentation

* Updated module in CI scripts

* Added deprecation warning

Make sure files are appropriately closed by PDBFile()

can't validate the that this object does anything more than simply write without
exceptions (i.e., we can't tell if the DCD file is actually _valid_)