#5 Improve implementation of constructors

[Markus Elfring]

I have noticed that a few assignments are used in a few constructor bodies.

Examples:
- Axis
http://auto-07p.svn.sourceforge.net/viewvc/auto-07p/trunk/auto/07p/plaut04/src/axis.c%2B%2B?revision=2022&view=markup

- Tube
http://auto-07p.svn.sourceforge.net/viewvc/auto-07p/trunk/auto/07p/plaut04/src/tube.c%2B%2B?revision=1313&view=markup

The recommended way for performing efficient construction is to use the initialisation list.
http://dietmar-kuehl.de/mirror/c++-faq/ctors.html#faq-10.6
http://cprogramming.com/tutorial/initialization-lists-c++.html
http://www.eng.cam.ac.uk/help/tpl/languages/C++/Thinking_in_C++/tic0143.html
http://www.informit.com/guides/content.aspx?g=cplusplus&seqNum=15&rl=1
http://goingware.com/tips/parameters/membervars.html