Ruby » Ruby master

• ext/bigdecimal/bigdecimal.c (BigDecimal_power): support non-integral
  exponent. fixes #3271
• ext/bigdecimal/bigdecimal.c (rmpd_power_by_big_decimal): ditto.
• ext/bigdecimal/bigdecimal.c (BigDecimal_power_op): add a function to
  only use for "**" operator.
• test/bigdecimal/test_bigdecimal.rb: add a bunch of tests for the
  above changes.
• ext/bigdecimal/bigdecimal.c (is_integer): add an utility function.
• ext/bigdecimal/bigdecimal.c (is_negative): ditto.
• ext/bigdecimal/bigdecimal.c (is_positive): ditto.
• ext/bigdecimal/bigdecimal.c (is_zero): ditto.
• ext/bigdecimal/bigdecimal.c (is_one): ditto.
• ext/bigdecimal/bigdecimal.c (is_even): ditto.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@32485 b2dd03c8-39d4-4d8f-98ff-823fe69b080e