Avoid waiting with a finite timeout and wait indefinitely in
dmon thread. When we need to unwatch we send a signal to a special
event meant to wakeup the waiting thread.
Some asserts are placed in case that can effectively occur
so we remove the assertion and we return false. In turn we
adapt the logic accordingly so when false is returned to add
a watch we do not open that directory.
We no longer use in Lite XL recursive directory monitoring as
it was a source of problems.
To enforce this at compile time we use the preprocessor to
remove the implementation of recursive monitoring for the Linux
implementation only.
Francesco Abbate