Block comments and configurable 'ignore this comment' flag

This commit adds the ability to define a block comment syntax
for individual languages (currently, only javascript -- I'm lazy)
Similar to singleLineComment, multiLineComment is an array, however,
unlike singleLineComment, it is not an array of alternatives; order
matters.  multiLineComment[0] opens a block comment, [2] closes it
and [1] is an optional beginning of line marker, ex:

/*
 * This is a block comment
 */

/* is the opener, */ is the closer, and * is a line marker

A line marker can also succeed or preceed an opener/closer, e.g.:

/**
 * Foo
 **/

Additionally, you can use block syntax on a single line:

/* This is a single line comment */

This opens up the possibility of adding additional languages
that only have block comments, like HTML or Handlebars