first pass at skipval/md5 ID implementation
prefix computed 'bounds' property as '_bounds'
major changes implementing skipval md5 ID scheme. NOTE: tasks no longer in random order.

- IDs are MD5 based with a 16 bit prefix (the "skipval"); 0=fixed, >0 is eligible for fixing
- objects' skipvals are incremented upon view, putting them at the back of the queue
- new mode: `node index.js --fixed` generates a JSON object of fixed IDs for use by import-csv.js, to preserve fixed status
- tasks are ordered by md5 hash right now, which means they are always presented in the same order