Add comment about file encoding
Feature comparison update
Mention scope differences to Python in Readme
Add comment explaining attach semantics
Fix list of existing operators

Fixes #30. `??` is not an operator, but `:=` is.
Merge branch 'operators' into develop
Update comment to reflect changed semantics
Fix documentation of import.attach option
Comment preference for files over nested modules
Specify imports necessary for doc generation
Add doc comments to test module for debugging
Implement doc parsing and display for modules

Add the following mechanisms:

 * Parsing of doc comments for a loaded module (`parse_documentation`)
 * Display module object documentation (`module_help`)
 * Transparent replacements for ``utils::`?``` and `utils::help`
Fix missing namespace qualification error
Fix module name in help title
Never attach exported submodules
Parse and attach documentation upon import
roxygen2 whimsically reformats my `DESCRIPTION`
Export and document help-related functions
Notch up version number, describe changes
Mention help system in README