added 1 func, & general improvements based on use

1. Added function ``zGetOpticalPathLength()``
2. Added return variable ``dataArea`` to the ``psfInfo`` named tuple
returned by ``zGetPSF() function``
3. Added default values to arguments of ``zSetSystem()`` function to
emulate behavior of Zemax application.
4. Some docstring clean up
Intermediate work on the bug
changes to address ipzCaptureWindow() problem

1. added function to use installed ImageMagick software if desired
2. removed blur option in ``ipzCaptureWindow()`` function
3. added functions to set and get ImageMagick settings
Merge pull request #35 from indranilsinharoy/capturewindowfix

capturewindowfix
modified .gitignore to ignore .ini files
modified how settings.ini works

Needed to modify how the settings.ini work because the file is not
ignored even after adding it to the .gitignore file, while it is still
in the repro.
cleaning
General code improvements
code improvements
added function to get OPD
Added a few functions in zdde.py and systems.py

1. Added functions ``zGetOperandRow()`` and ``zSetOperandRow()`` to
zdde.py
2. Added ``zMakeBeamExpander()`` function in systems.py
3. Rearranged functions based on categories in zdde.py
Updated minor version number
slide formatting change
Merge branch 'master' of https://github.com/indranilsinharoy/PyZDDE

Conflicts:
	pyzdde/zdde.py