add tui module and example, add contex manager cd and the method run_file in helper

import vendor modules only once during import

change text color for the method cad_wireframe in geometry_plot_pylab and add hide key

docs/source/index.rst

@@ -15,8 +15,39 @@ Welcome to pylib's documentation!
 
 
 Indices and tables
-==================
+------------------
 
 * :ref:`genindex`
 * :ref:`modindex`
 * :ref:`search`
+
+
+
+tui
+---
+
+pylib/tui.py is the main module for tui 'terminal user interface' programs.
+
+* curses package (for Windows install windows-curses) is the underlying main
+  package to build terminal programs. The curses package can also be used
+  directly.
+
+  * Windows (Anaconda):
+
+    * ``C:\PathToAnaconda3\condabin\conda.bat activate base``
+    * ``python -m pip install windows-curses``
+    * https://github.com/zephyrproject-rtos/windows-curses
+
+* drawille package is used to draw with braille characters (dottet and quasi-
+  line charts). Make sure you use a font with Unicode Braille characters. For
+  Windows e. g.: NSimSun, MS Gothic.
+
+  * Install: ``python -m pip install drawille``
+  * Windows (Anaconda):
+
+    * ``C:\PathToAnaconda3\condabin\conda.bat activate base``
+    * ``python -m pip install drawille``
+
+* drawblock.py is used to draw with block characters (histogram).
+
+example/tui.py is an example script to build a terminal program.