add isBinary to language def
enable file extensions for binary file types
 review comments:
- factor dupe code into function
- also handle file names for binary files
- do not register binary flagged lang as pending
- added defineLanguage() docs for isBinary flag
Modify the FileSystemEntry.exists callback to take an additional error parameter.
- remove comment in wrong place.
- Spell CodeMirror in camel case
Update JSDoc
Merge pull request #5966 from adobe/iwehrman/add-err-parameter-to-exists

[FileSystem] Add an error parameter to the FileSystemEntry.exists callback
Merge pull request #5957 from adobe/couzteau/fix-5749-LM-mode-warning

Couzteau/fix 5749 language manger mode warning on binary file