Problem:    Ruby Kernel.#p method always returns nil.
Solution:   Copy p method implementation from Ruby code. (Masataka Pocke
            Kuwabara, closes #3315)

Problem:    Now Ruby build fails on other systems.
Solution:   Always define rb_intern. (Ken Takata, closes #3275)

Problem:    Ruby build fails when ruby_intern is missing.
Solution:   Do not use ruby_intern2. (Ken Takata)

Problem:    Ruby error does not include backtrace.
Solution:   Add an error backtrace. (Masataka Pocke Kuwabara, closes #3267)

Problem:    Ruby converts v:true and v:false to a number.
Solution:   Use Qtrue and Qfalse instead. (Masataka Pocke Kuwabara,
            closes #3259)

Problem:    Preferred cursor column not set in interfaces.
Solution:   Set w_set_curswant when setting the cursor. (David Hotham,
            closes #3060)

Problem:    Stderr output from Ruby messes up display.
Solution:   Turn the stderr output into a Vim message. (Masataka Pocke
            Kuwabara, closes #3238)

Problem:    compiler warning for unused arguments and missing prototype
Solution:   Add UNUSED.  Add static.

Problem:    Segmentation fault when Ruby throws an exception inside :rubyfile
            command.
Solution:   Use rb_protect() instead of rb_load_protect(). (ujihisa,
            closes #2147, greywolf, closes #2512, #2511)

Problem:    Mac features are confusing.
Solution:   Make feature names more consistent, add "osxdarwin". Rename
            feature flags, cleanup Mac code. (Kazunobu Kuriyama, closes #2178)