ENH: Added discrete Lyapunov transformation solve
CLEAN: Documentation and style improvements.
TST: Added test cast for large matrix (M=11).
PEP8: Fixed too many spaces
Added documentation and test for using FortranFile.read_record to read in mixed type records
DOC: Clarify docstring for `sigma` parameter for `curve_fit`

Fixes #3682
Merge pull request #3920 from chatcannon/optimize_doc

DOC: optimize: Clarify docstring for `sigma` parameter for `curve_fit`
Fixed Docstring issues in linprog (Fixes #3905).

* removed superfluous second "Returns" section
* reordered the sections to match the docstring standard
Merge pull request #3922 from venthur/fix-3905

DOC: fix docstring issues in linprog (Fixes #3905).
Merge pull request #3865 from astrofrog/fortran-mixed-records

DOC: io: document and test reading record inputs in FortranFile
Merge pull request #3748 from ChadFulton/bilinear_lyapunov

ENH: linalg: add bilinear transformation method for solving discrete lyapunov

The existing direct solution method to the discrete Lyapunov equation
solve_discrete_lyapunov is not good for large matrices since if the
original matrix is MxM, the current method requires solving a linear
system of order M^2.

This request adds a solution method that uses a bilinear transformation
from the discrete to the continuous Lyapunov equation, which can then be
solved using the existing continuous solver which can take advantage of
the LAPACK *trsyl routines.

It allows selecting between the two methods ('direct', 'bilinear'), and
defaults to using the direct method when the input matrix dimension is
less than 10 and the bilinear method otherwise.
Fixed -Wmaybe-uninitialized warning in FFT

It would be nice to refactor these to make the code easier to understand,
possibly that would also allow the compiler's static analysis to spot
that these maybe-uninitialized warnings are spurious
Fixed a 'rank mismatch' warning
TST: add a script to test the runtime of tests for each submodule.
tmp - time_testsuite sysexit
TMP: call time_testsuite.py from runtests.py
TMP: only keep one run of full testsuite, in order to time TravisCI test run.