Bash is modified to call out to Guile code whenever the user enters a
command-line; the code has the opportunity to fix up the command line in
any way. The Guile code is under the ibash-scheme directory, all is all
newly created in this delta.
* configure: why does this have to be in here?
* configure.ac: look for guile and libguile.
* eval.c: call guile_main and load ~/.bash_guile.scm.
* shell.c: perform call-outs prior to executing command lines.
* ibash-scheme/ibash-callout.scm: first call-out.
* ibash-scheme/remote-sender.scm: second call-out.
* ibash-scheme/ibash-server.scm: central intelligence service.
* ibash-scheme/modules/i-bash: transform ib -> i-bash.
* ibash-scheme/modules/cd: cd command line processor.
