Supporting IO.ungetbyte
Merge pull request #697 from josedonizetti/support_ungetbyte

Supporting IO.ungetbyte
Merge pull request #695 from atambo/regex_options_fixed_none

Regexp#options should include FIXEDENCODING and NOENCODING when enabled
Merge pull request #698 from atambo/range_first_error_on_negative

Range#first should raise an ArgumentError when count is negative
Merge pull request #699 from atambo/range_each_error_on_time

Range#each should raise a TypeError if the first element is a Time object
Merge pull request #700 from atambo/numeric_div_error_on_zero

Numeric#div should raise ZeroDivisionError for 0
Merge pull request #701 from atambo/untag_math_specs

Untag passing Math.cbrt and Math.gamma specs
Merge pull request #703 from atambo/kernel_abort_should_set_message

Kernel.abort should set the exception message to the given message
Kernel.exec should raise an ArgumentError if the command includes a null byte