Add Travis config
Add a README describing the motivations and purpose of the hunspell branches
Use .hgignore as .gitignore
Add --enable-hunspell configure flag

In order to use the pkg-config macros, aclocal has to be run before autoconf.
This copies pkg.m4 to aclocal.m4 in src/ so it's available for autoconf, which
means it needs to be removed in the autoconf target.

Signed-off-by: James McCoy <vega.james@gmail.com>
Makefile: Add HUNSPELL_CFLAGS/LIBS

Signed-off-by: James McCoy <vega.james@gmail.com>