Sysinfo

Added more accurate system information detection. Useful for error reports (we can ask users to report the output of ./map-server --version rather than having to ask for OS, architecture, revision, whether they recompiled their server, etc), as well as for the stats server (to learn about the users preference in matter of OSes and compilers, to figure out which ones should be given a higher priority during tests).

[Note: please do not merge until reviewed. The commits need to be rebased]