desktop entry proposal: TerminateSafe=true key

[Daniel Bo]

Freedesktop is supposed to be OS-agnostic. Setting a key in the
.desktop file will signal the compliant desktop to change the kill
priority on the OS, whether that OS is Linux, BSD, or even Haiku. Some
OSes may not support this function, and it can be ignored.

For the Linux use case, the desktop launcher checks the kill priority
in the .desktop file and modifies oom_adj.

This seems perfectly sane.

Daniel