Missing updates from version 5.74, corrected warning/error for latest versions of Python 2.7 and added instructions about Ubuntu 16.04

[lebarsfa]

This repo was missing updates from 5.74 release available on http://sourceforge.net/projects/vpythonwx/files/5.74-release/visual-5.74_release.tar.bz2/download, so I propose to integrate them here.

Also, on recent versions of Python 2.7,

import visual

may give a warning

/usr/local/lib/python2.7/dist-packages/vis/materials.py:70: FutureWarning: comparison to `None` will result in an elementwise object comparison in the future.
  self.__setattr__(key, value)

which seem to become an error

/usr/local/lib/python2.7/dist-packages/vis/materials.py:70: ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()

on more recent versions, so I propose to integrate a fix from the code of vpython-wx.

I added instructions in INSTALL.txt to be able to rebuild easily on Ubuntu 16.04. However, for Ubuntu 18.04 compatibility, see #12.