* plugins/fn-random/functions.c: Include rangefunc.h.

* plugins/guile/plugin.c (gnm_guile_catcher): Remove unused var 'len'.
(plugin_init_general): Remove unused var 'cat'.

* plugins/guile/guile-support.c: Include position.h.

* plugins/qpro/qpro-read.c: include gutils.h.

* src/search.c: Include gutils.h.

* src/tools/simulation.c: Include rangefunc.h.