s/F17/F18/g
Adjusted CONFIGURE_F18.bash instructions to match the current name of
the script.
Don't specify 'z' as an option to tar. Modern version of tar deduce the
type of compression in use, so specifying 'z' explicitly prevents the
use of tarballs which are not gzipped. When using the 'f' option for tar,
the next argument should be the filename.
* Updated CONFIGURE_F18.bash to build liblightgrep from the 1.2.0 release.

* Modified build_mingw function not to construct download URL from a base
URL and a tarball filename. Doing it this way is brittle, since the
filename might be set by a Content-Disposition header instead of by the
URL.

* Run bootstrap.sh only if configure doesn't exist.
Ignore generated src_win/BEViewerLauncher.exe.