…iquely

Changes in this patch:

* Name.Quoted and Name.Quoted.Escape are introduced as non-standard tokens
* HTML and LaTeX formatters were confirmed to provide default formatting
  if they encounter these two non-standard tokens. They also add style
  classes based on the token name, like "n-Quoted" (HTML) or "nQuoted"
  (LaTeX) so that users can add custom styles for these.
* Removed "\`" and "\\" as schema object name escapes. These are relics
  of the previous regular expression for backtick-quoted names and are
  not treated as escape sequences. The behavior was confirmed in the
  MySQL documentation as well as by running queries in MySQL Workbench.
* Prevent "123abc" from being treated as an integer followed by a schema
  object name. MySQL allows leading numbers in schema object names as long
  as 0-9 are not the only characters in the schema object name.
* Add ~10 more unit tests to validate behavior.

Closes pygments#1551

Also, add tests that confirm correct behavior. No tests failed before
or after removing the '$' match in the regex, but now regexlint isn't
complaining.

Removing the '$' matching probably depends on the fact that Pygments
adds a newline at the end of the input text, so there is always something
after a bare integer literal.