- switch Gemfile source from :gemcutter to 'https://rubygems.org'
(silences security warnings)
- bump version number prior to 4.0.0 release
- drop unnecessary `encoding` magic comments from source files
- drop support for versions of Ruby < 2.0.0
- make sure string_from_str() returns a string that is marked as UTF-8
encoded; otherwise a string marked as "ASCII-8BIT" will be returned
and string comparisons will fail; this was noticed due to the
breakage of the "redlink" specs which were failing otherwise
- drop references to now-dead iconv
- swap some `proc` for `Proc.new`
- swap some `lambda` for `expect` in the spec suite; this is not
merely cosmetic as the LocalJumpError tests were failing without it
- drop some "should" from `it` descriptions in the spec suite
- loosen brittle TypeError assertions in spec suite which would
otherwise have failed (the error message has changed since 1.9.x)
- always use a space after a comma separating arguments
- replace `not` and `or` with `!` and `!!`
- use `__dir__` in lieu of `File.dirname(__FILE__)`
- update copyright year ranges in touched files
- update docs prior to release