configure: Set a default $prefix

This enables configuring without setting the --prefix= argument.
git: Don't track generated file
man/emu: Remove empty section
man/emu: New tagline
man/emu: Remove redundant "See also"
Put man pages into a Documentation/ subdir
Put test error output in test.log
Move auxiliary scripts into scripts/ subdir
scripts/todo: Don't echo tempfile
man/emu-init: Minor rewording of template dir sec
man/emu-init: Don't use dollar sign command prefix
README: Separate requirements and installation secs
Move tests/ directory to test/
scripts/run-tests: Set test_files correctly
make: Remove redundant 'V=[01]' help
emu/log: Set stack dir globally

It is required by libemu
Source libemu location relative to script

This means that we don't need to perform the @LIBEMU@ substitution.
Don't autotool the emu/ scripts

Use libemu.sh.in as the holding place for generics which require
substituting during the configuration phase.