longer names for identifiers

[elfring]

The C programming language does not support namespaces. The consequence is that all API designers must be very careful to avoid naming collisions.
Unfortunately, the source files for the JkDefrag library contain names that might collide with identifiers in other software modules.

Examples:

• YES, NO
• RUNNING, STOPPED
• TreeFirst, TreeInsert
• DefaultDebugMsg

I propose to choose a naming convention that will be a bit safer for further software development.

[jeroen]

The current names do not collide with any of the Microsoft libraries. That's good enough for me.

[elfring]

I propose to lower the probability for name clashes even more. There are more software modules than only Microsoft ones available that want to cooperate with your library without unpleasant surprises.

[elfring]

The values "YES" and "NO" can be replaced by standard specifications "true" and "false" or completely avoided by shorter wording of predicates.

Some global variables and functions that are only used in a single translation unit can be hidden in unnamed namespaces.