utilities: RadixTree can now optionally operate in a case-insensitive manner.
utilities, process: Thread::join and Thread::detach now exist, and RequestQueues can now be halted. Termination of threads has been adjusted.

Also, the removal and cancellation of requests that a Thread owns has been reworked. This is exceptionally subtle code and I expect it to be modified again.
src: avoid leaking Threads by detaching them after creation. Many of these could actually be stored and joined, in the longer-term.
vfs: provide a way for filesystems to specify themselves as case-sensitive or not (default true)
vfs: default Directory cache now uses Filesystem case sensitivity to determine whether the RadixTree should be case sensitive.