Mark all symbols as hidden except the main entry point

This avoids conflicts with other gems that may have some of the
same symbols, such as redcarpet which also uses houdini.
Merge pull request #32 from tomhughes/symbolic

Link with -Bsymbolic to make sure we use the local copy of houdini
Use Minitest::Test.  Use https for gems source.
Merge pull request #45 from jadeatucker/Remove_deprecation_warnings

Use Minitest::Test.  Use https for gems source.
require fairly new minitest
use rb_str_new_with_class instead of setting klass
Merge pull request #48 from charliesome/ruby-2.1

Use rb_str_new_with_class instead of setting klass
required ruby version is > 1.9.3
remove 1.8 compatibility code
bump version
allow rubinius 1.9 failures - rbx doesn't have rb_str_new_with_class
Merge pull request #49 from charliesome/f u c k 1 8

Drop Ruby 1.8 support
mark globals /cc #48
add script/bootstrap
note about 1.9.3+
bump version for 1.0.0
remove changelog in favor of releases
Fix ruby version requirement
Merge pull request #52 from bricker/master

Fix ruby version requirement. Fixes #51
Add license to gemspec