Complete the prototype removal in ca1431.
The script prevents SWIGTOOL=gdb from working as gdb can't be used to
debug a shell script, it requires a binary.
Add support for SWIGTOOL in all the examples.
SWIG_LIB_DIR and SWIGEXE must now instead be set by all Makefiles.
See issue #473.
After the documentation update on how to utilize the director feature with
commit @17b1c1c the 'callback' and 'extend' examples needed an update as well.
