Make git ignore node_modules
SIL macros: implement INSERT
Add Snoflake.config and Snoflake.log

Snoflake.config will hold various configuration variables. At the moment, the
only configuration variable is 'debug'. Its value affects Snoflake.log: when
Snoflake.config.debug is false, then Snoflake.log is a no-op; when true, then
Snoflake.log delegates to console.log.