If SERENITY_BUILD is not set or empty, SERENITY_BUILD is treated as if
it was set to '.'.
`run.sh` will cd to SERENITY_BUILD before running the emulator.
Also, export SERENITY_BUILD in `Meta/CLion/run.sh` since we are using it
in `Meta/run.sh`.
Also, allow using a different bochs configuration file by setting the
SERENITY_BOCHSRC variable.
We don't need to copy `run.sh` and modify it: we can just set
environment variables.
Now, we don't have to modify two files everytime we make a change to the
run.sh script.
Also make SERENITY_BUILD overridable with environment variables,why not?
This commit updates CLionConfiguration.md and NotesOnWSL.md so that
they comply with new build system. In addition to that, the WSL doc
is updated to include instructions to run qemu (and serenity) natively
on Windows, without needing an X-window server.
