Fix copyability of Constant objects.
Don't warn about missing config file if there isn't supposed to be one.
Initial split of optimizers/statistics
PEP 8 and docs changes
add example of a user-defined statistic function
Add changelog entries for the changes introduced by this PR
Fix up the examples a bit to reflect the current code.  I agree with @taldcroft that these examples expose an unfortunate degree of complexity involved in creating new Fitters, such that it is not really at a point where casual users can do it.  But these docs are still useful to have for developers to look at--in the future I hope to try to hide more of the sausage-making if I can.  Also redid the section headings per the preferred formatting.
Remove this no longer relevant comment
Fix typo
Fix a few more references to NonLinearLSQFitter
Just a little test module cleanup
A little more cleanup.  Use the assert_ function directly instead of going through a 'utils' module.  Use the NumpyRNGContext where appropriate.
As requested, adds a simple test for the SimplexLSQ fitter.
A slew of minor documentation fixes--many of them for things pointed out by @cdeil in #2441, but also including several other mistakes I found while reading through the docs.
Hack to basically restore the functionality of running 'make' from inside the docs/ directory without having explicitly installed astropy_helpers first.  For general cases, such as building the docs on rtd, it remains preferable to simply install astropy_helpers first.
Fix use of backticks in recent WCS changes
Use MiniConda for setting up dependencies
Install all sphinx dependencies, and test old Numpy versions only with Python 2.7
Add python 3.2 build
Simplify miniconda installation and always point to latest version