Add inotify support

[rainer]

Supporting inotify would allow to get rid of the I/O load associated with regular file system scans.

[rainer]

Initial inotify support added with changeset [367]. Compiles, but has not been tested yet.

[rainer]

Uhmm.. two missing files added with changeset [368].

[rainer]

Changeset [369] fixes a silly bug in sh_inotify_read.

[rainer]

Changeset [371] fixes a couple of remaining issues with inotify support.

[rainer]

Changeset [372] covers directories that should be watched as files only in the configuration. Also don't remove directory watches if files in the directory are removed (duh..), and re-write the baseline database if we are in 'update' mode.

[rainer]

Changeset [373] fixes the handling of inserted subdirectory trees, and adds the capability to re-expand and re-scan the list of files configured to be checked.