move build_aux to build-aux

* build_aux/*: moved
* configure.ac (AC_CONFIG_AUX_DIR): modified
Add gnulib bootstrap script

* bootstrap.conf: new file
* cfg.mk: new file
* gnulib: updated
Don't try to build build_aux

* Makefile.am (SUBDIRS): modified
* configure.ac (AC_CONFIG_FILES): modified
Don't capitalize error messages

* src/curl.scm.in (curl-easy-setopt): modified
Don't use @ in Makefile.am

* src/Makefile.am: modified
* test/Makefile.am: modified
Update .gitignore

* .gitignore: modified
* build-aux/.gitignore: new file
* doc/.gitignore: new file
* lib/.gitignore: new file
* m4/.gitignore: new file
bootstrap requires a README-hacking

* README-hacking: new file
Rename curl.texi -> guile-curl.texi

* doc/Makefile.am (TEXINFOS): modified
* doc/curl.texi: name before
* doc/guile-curl.texi: name after
Clean up options constants

* doc/guile-curl.texi: clean up options
* src/const.c: modified
* src/curl.scm.in: modified