Implement a logging framework
- Logger is intended to collect messages e.g. from file loading, and then access them from elsewhere to display them to the user
- a "singleton/globalton" Logger can be accessed by calling Logger.getLogger(), just require() the Logger module
- API supports several levels: log(), warn(), error(), debug()
- messages are collected in an array, and written to the browsers' console
- debug messages are an exception in that they are only logged to console, not stored in the array
Use Logger in CellrefParser
- send messages to logger instead of dumping directly to console
Don't treat missing site reference as fatal error, continue file parsing
Display collected log messages when file load is complete
Use Logger in FileLoader
Merge branch 'logging-framework'