Salabim 19.0.0 released.

[Ruud van der Ham]

I have just released salabim 19.0.0, which is a package for discrete event
simulation and animation. See www.salabim.org for details.

Release notes
=============
New functionality
-----------------
Queues now register the arrival rate and the departure rate, defined as
   number of arrivals since last reset / duration since last reset
   number of departures since last reset / duration since last reset
The following methods are available:
    Queue.arrival_rate()
    Queue.departure_rate()
The registration can be reset with
    Queue.arrival_rate(reset=True)
    Queue.departure_rate(reset=True)
Note that this functionality is completely independent of the monitoring.


Added functionality
-------------------
Video production now supports also the creation of a series of individual
frames, in
.jpg, .png, .tiff or .bmp format.
By specifying video with one of these extensions, the filename will be
padded with 6 increasing digits, e.g.
    env.video('test.jpg')
will write individual autonumbered frames named
    test000000.jpg
    test000001.jpg
    test000002.jpg
    ...
Prior to creating the frames, all files matching the specification will be
removed, in order to get only
the required frames, most likely for post-processing with ffmpeg or similar.

Note that individual frame video production is available on all platforms,
including Pythonista.


The method Environment.delete_video() can be used to delete all
autonumbered files, like
    env.delete_video('test.jpg')
will delete
    test000000.jpg
    test000001.jpg
    test000002.jpg
    ...
If this method is used with any other file type, like .mp4, the file does
not need to exist (i.e. no action is taken then).


Announcements
-------------
>From this version, salabim uses the CalVer (see www.calver.org) standard
for the version number.
This means that versions are numbered YY.major.minor, where
  YY is the year of the release minus 2000
  major is the major version number (0 based)
  minor is the minor version number (0 based)

>From this version, legacy Python (<= 2.7) is no longer officially supported.