Streaming theory – r87

Revision 87 just adds a few notes on the streaming theory I'm pondering to implement. The principle is creating stream filters and cascading star data in pipes of one stream filter after another. The theory should be analogous to the pipe streams of Unix, except the filters are not normally written in a Unix shell, even thought that is possible. Instead of using PP3:s simple state setup and having a fixed few steps cascade (1. set "parameters", i.e. any generation constants, 2. delete and add objects, 3. "compute and draw"), the filters and the pipe streams shall be configurable in the intended programming language of mkmap.