#598 Merge PCRaster sub-projects into one PCRaster project

[Kor de Jong]

For historical reasons, the PCRaster project is divided into multiple sub-projects (devenv, rasterformat, xsd, dal, aguila, ...). At the time, this seemed like a good idea, but not anymore. It complicates the build process and the version management.

At least some of the sub-projects should be merged into a larger project.

Devenv is tricky. Maybe create a project that only has scripts and configuration stuff, but no code.