Log Message:
Update to 5.1.0

Changelog:
# General improvements

    The Octave plotting system now supports high resolution screens, i.e., those \ 
with greater than 96 DPI which are referred to as HiDPI/Retina monitors.

    Unicode character support for files and folders in Windows.

    A new core function movfun will apply a function to a sliding window of \ 
arbitrary size on a dataset and accumulate the results. Many common cases have \ 
been implemented using the naming scheme movXXX where XXX is the function that \ 
will be applied. For example, the moving average over a dataset is movmean. New \ 
moving window functions:

    movfun movslice movmad movmax movmean movmedian movmin movprod movstd movsum \ 
movvar

    The fsolve function has been tweaked to use larger step sizes when \ 
calculating the Jacobian of a function with finite differences. This leads to \ 
faster convergence.

    The ranks function has been recoded for performance and is now 25X faster. \ 
In addition, it now supports a third argument that specifies how to resolve the \ 
ranking of tie values.

    The function randi has been recoded to produce an unbiased (all results are \ 
equally likely) sample of integers. This may produce different results in \ 
existing code. If it is necessary to reproduce the exact random integer sequence \ 
as in previous versions use

    ri = imin + floor ((imax - imin + 1) * rand ());

    The function isdefinite now returns true or false rather than -1, 0, or 1. \ 
To test for a positive semi-definite matrix (old output of 0) check whether the \ 
following two conditions hold:

    isdefinite (A) => 0 and isdefinite (A + 5*TOL, TOL) => 1

    The intmax, intmin, and flintmax functions now accept a variable as input. \ 
Existing code to query the range of an existing variable can be simplified by \ 
removing the call to class that was previously required. For example defining \ 
the variable x = int8 (3) in the workspace, calls like

    range = [ intmin(class(x)), intmax(class(x)) ]

    can in Octave 5 be simplified to range = [ intmin(x), intmax(x) ].

    The path handling functions no longer perform variable or brace expansion on \ 
path elements and Octave’s load-path is no longer subject to these expansions.

    A new printing device is available, "-ddumb", which produces ASCII \ 
art for plots. This device is only available with the gnuplot toolkit.

# Dependencies

    The GUI requires Qt libraries. The minimum Qt4 version supported is Qt4.8. \ 
Qt5 of any version is preferred.

    The OSMesa library is no longer used. To print invisible figures when using \ 
OpenGL graphics, the Qt QOFFSCREENSURFACE feature must be available and you must \ 
use the qt graphics toolkit.

    The FFTW library is now required to perform FFT calculations. The FFTPACK \ 
sources have been removed from Octave.

Matlab compatibility
* Many improvements.