There were two issues:

1. Github flavored markdown calls Objective C `objective-c`
2. The gfm.js mode didn't include `-` in its fenced code block regex

Additionally, test/index.html did not import the mode/meta.js file,
which prevented mode lookup by name from working in unit tests.

Issue #3932

BUCK, BUILD, *.BUILD and *.bzl files are build files for the three build
systems mentioned, and they are all valid Python files.

Closes #3922

Closes #3914

The 6 "n"s are reported as suspicious code by Closure Compiler.
They can just be empty statements instead.

This eliminates a warning from Closure Compiler.

Issue #3911

Added tests and fixed some issues uncovered by testing.

corrected angle bracket matching in operators (fixes block comments)
corrected digit matching regex
corrected spelling of 'identifier' in grammar dictionary
notCharacterOrDash explicitly includes lowercase characters
improved variable matching
splatted variables now match
bare '$' and '@' are errors, not variables
moved single-quoted string processing into tokenSingleQuoteString
incomplete strings are errors now
empty strings are no longer errors
added support for here-string interpolation with nesting support
added highlighting for splatted vars
removed arbitrary stream advancement prior to default error in tokenBase
enabled folding braces

Closes #3878

To configure the inner mode.

Closes #3893

Closes #3876

Issue #3869

`text/troff` is the standard approved by IANA. Also add some
non-standard MIME types.
https://bugs.freedesktop.org/show_bug.cgi?id=5072

See http://spec.commonmark.org/0.24/#list-items

Closes #3833

Issue #3862

Closes #3861

Closes #3864

This allows findModeByName to work for edn and seems more consistent
with how JSON is handled.

Closes #3853

 * Support nested block comments.
 * Improve number and operator parsing.
 * Improve string parsing.
 * Style brackets correctly.
 * Improve #-words.