dynamic module loading implemented

Rev: src/ChangeLog:1.8
Rev: src/Makefile.src:1.10
Rev: src/configure.in:1.7
Rev: src/dynamic_load.c:1.1
Rev: src/dynamic_load.h:1.1
Rev: src/machine.h.in:1.6
Rev: src/main.c:1.7
Rev: src/stralloc.c:1.2
Rev: src/stralloc.h:1.2