After initialization, we get following base directories list (in priority order):
* Writable preference path
* User defined paths (cmd-line and configuration)
* Platform defined paths (such as /usr/share/Descent3 on Linux or Steam installation paths on all platforms (TBD))
* Directory of executable
Removing `-setdir` and `-useexedir` as redundant (both can be replaced with `-additionaldir` option).
Inline the only usage of `loki_getprefpath()`, and use `Base_directory` (controlled by `-setdir`) instead of `loki_getdatapath()`.
Inline or eliminate some other code that became empty/unused with loki removal.
Join the license header with historical comments using a separator so IDEs can correctly parse the initial header.
Also use .gitattributes to ensure all files are LF.
