* Fixed `render_list` build needs `libm`
* Added tests
* Updated man page
* Created function to set double
* Cleaned up / optimized a bit
* Removed `--dont-render` option
_Also updated all render\_* apps to_:
* Use `MAX_ZOOM` rather than hard-coded values for `--max-zoom`
* Print `metatile` rather than `meta tile`
* Add missing `--help` output to `render_expired` & `render_list`
* Remove redundant `--help` output from `render_list`
_Also_:
* Added checks for `min` & `max` `x`, `y` & `z` tile coordinate options in order to:
* Ensure they are integers
* Ensure they are positive
Resolves#387