Corrfitter

===========================

- New fitter fastfit(...) which estimates E and a*b for the dominant term
in a correlator at large t (usually the smallest E). This is done by
marginalizing every term in the correlator except for the leading term,
and then solving for E using the exact formula for the leading term. This
function is useful for a quick estimate and is often almost as accurate
as the result of a full fit. Added unittests for this function.

- Removed bugs in marginalization code for anti-periodic functions.

- Polished some of the documentation.

=================================
This is a minor update that has no effect on most applications. It does
however significantly improve testing.

- 'make tests' now runs a completely new set of tests organized using
Python's standard unittest module (so the tests can also be run using the
standard 'python -m unittest discover'). Unlike the old tests, the new
ones are hardware independent and so should work with pretty much any
system. The old tests are now in the directory called 'examples' and are
run using 'make run-examples'.

- Fixed a bug where Corr3s with symmetric_V=True caused CorrFitter to crash
when using marginalization (i.e., specifying nterm in CorrFitter).

- Allow non-string labels for y-axis in CorrFitter.display_plots().

===========================
This version now works with python 3, which seems slightly faster than
python 2 but not so much that one needs to convert immediately. Other
changes:

- Anti-periodic correlators can now be fit by specifying a negative tp in
Corr2 (and, less usefully, Corr3).

- The test code was rewritten to make it compliant with python 3. This
entails using new serialization code in lsqfit v4.2.6. The tests will
fail with earlier version of lsqfit.

===========================
This version updates the output from the tests to deal with format changes
in lsqfit 4.2.3. The code (corrfitter.py, not necessarily the test files)
seems to work with python3 but this has not been carefully explored yet.

========================
Changes to accommodate changes introduced in lsqfit 4.2:

- svdcut and svdnum can be 2-tuples now (see lsqfit.nonlinear_fit)

- GPrior replaced by gvar.BufferDict

- removed module dataset as it is no longer needed by corrfitter, which now
uses gvar.dataset.Dataset and gvar.dataset.avg_data instead. A simplified
replacement for the old module is included (called dataset.py) for use
with old code. It is not installed by 'make install'; it can be installed
if needed (for old code) using "make install-dataset" (or "python
dataset-setup.py install --user"). Don't install it if you don't have old
code.

Created by G. Peter Lepage, Cornell University, on 2010-11-26.
Copyright (c) 2010-2015 G. Peter Lepage.

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
any later version (see <http://www.gnu.org/licenses/>).

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.