GeezerVison

Only have manual test for the time being.

Found some existing problems when using space as delimiter:

- `%Q foo\ \\\ bar ` is not detected as string.
- They can't go across lines, so folding is not needed.

- Add back double quote coverage.
- Remove invalid `%W foo ` syntax.

Aim to test this line:
https://github.com/vim-ruby/vim-ruby/blob/8775819/syntax/ruby.vim#L124

Case of ternary operation (8c1c484) doesn't fold with below format:

```ruby
  /
    foo
    \/
    \\\/
    bar
  /s
```

so test `?` `:` separately.

Aim to test this line:
https://github.com/vim-ruby/vim-ruby/blob/8775819/syntax/ruby.vim#L125

Not sure the purpose, just write case to reproduce the regex.

For multiline 'string' "string" and `shell command`.

It's hard to enumerate every case, so just separate to valid/invalid
section, see example file for detail.

3 types share one example file, but can be config separately.

Put there simple blocks into one `blocks` example.

For `for`, `while` and `for` loops.

Known `=begin xxx` should be valid comment, but seems not detected well
when ruby_no_comment_fold is set.

Should remove `percent` level under 'etc/examples' directory.

* master:
  Match much more complicated structures in block's arguments in a very simple way.
  Fix issue with `end`s in multiline ERB output
  Add support for Ruby 2.3 heredoc <<~ syntax
  Add support for RSpec 3.4 to compiler
  Improve rubyMultilineComment performance
  Fix whitespace delimited percent 'strings'
  Don't add second .rb to filenames
  Match RSpec failures with index greater than 9
  Account for new safe navigation operator
  Highlight character literals in Range literals
  Highlight Rational and Complex literals
  Highlight all of the unary methods.
  Don't highlight `.?c` as a "character" literal.
  Set browsefilter for gui_gtk
  Remove ruby_spellcheck_strings related duplication

Conflicts:
	syntax/ruby.vim

- Whitespace delimited `%` literal, a696da8
- Heredoc with `<<~` form, a28f8df

Developer can generate these files if needed, follow instruction in
etc/example/generators.