spatialite support

[fgregg]

Thanks so much for this great tool. Would love for it to work with spatialite databases.

[gvoysey]

currently ( on litecli 1.9.0):

select load_extension('/usr/lib/mod_spatialite.so');

returns not authorized, even though litecli has been installed with a python that has spatialite support enabled and was built with:

export PYTHON_CONFIGURE_OPTS="--enable-shared  --enable-loadable-sqlite-extensions"
export LDFLAGS="-L/usr/local/opt/sqlite/lib -L/usr/local/opt/zlib/lib"
export CPPFLAGS="-I/usr/local/opt/sqlite/include -I/usr/local/opt/zlib/include"```