bugfix: writer pool race condition between get() and close() could produce NPE.

- OS-level remove and truncate file methods exposed [OSX so far]
- bugfix

memory page size used by var() (variance) can be set via config file

Updated and tidied up examples. They split into two main categories: append data and query data. I will be adding more examples, so stay tuned into this.
Added match() function to extract data from text using regex.