Revert "issue #17: solve Symbol not found: _sqlite3_enable_load_extension by #ifdef-ing it out by default; erlang-sqlite3 will need configure-esque feature detection via http://www.sqlite.org/c3ref/compileoption_get.html or http://www.sqlite.org/pragma.html#pragma_compile_options"

This reverts commit 4ef228c8a39cd8b18392dd4e3f18f3dcee862d83.
issue #17: solve Symbol not found: _sqlite3_enable_load_extension by #ifdef-ing it out by default; erlang-sqlite3 will need configure-esque feature detection via http://www.sqlite.org/c3ref/compileoption_get.html or http://www.sqlite.org/pragma.html#pragma_compile_options