Ruby-Libthai update

The first version of Ruby-Libthai has appeared since 15th February 2003. Until today, only another one method was added, i.e., LibThai::tis?.

Now we can do something like below:

require 'libthai'
"abcd".each_byte{|c|
   p LibThai::tis?(c)
}

More infomation: http://th.lug.wikia.com/wiki/Ruby-Libthai