Improvements in CapacityScaling.

Main changes:
- Use -potenital[] instead of potential[] to conform to the usual
terminology.
- Change the name of private members to start with "_".
- Change the name of function parameters not to start with "_".
- Remove unnecessary documentation for private members.
- Doc improvements.

 Document: lemon-refman

 Title: LEMON Reference Manual

 Author: LEMON Development Team

 Abstract: Documentation of LEMON.

 Section: unknown

 Format: HTML

 Index: /usr/share/doc/lemon/html/index.html

 Files: /usr/share/doc/lemon/html/*.html