fix missing sentinel warning in ncurses.c
cpan default mirror is now www.cpan.org

 * cpan.perl.org is now an HTML 301 Redirect to www.cpan.org, causing
   cpans to segfault when it tries to gunzip it.  Update default
   mirror to www.cpan.org.
get build workng on OS X

 * move linker flags to LDFLAGS
 * use the osx-provided curl
Makefile cleanup

 * remove -I.
 * remove commented-out code
 * whitespace / nitpicky fixes
Merge pull request #4 from felliott/misc_fixes

Misc fixes