Extract range type check functions

	---
	 range.c | 55 ++++++++++++++++++++++++++++++++++++-------------------
	 1 file changed, 36 insertions(+), 19 deletions(-)

	[Bug #19533] Fix infinite range inclusion with numeric value

	---
	 range.c                 | 10 +++++++---
	 test/ruby/test_range.rb |  2 ++
	 2 files changed, 9 insertions(+), 3 deletions(-)

	[Bug #19533] Add spec of infinite range inclusion

	---
	 spec/ruby/core/range/case_compare_spec.rb | 6 ++++++
	 1 file changed, 6 insertions(+)

Fixes [Bug #18983]

[Bug #18994]