moved everything into /trunk/ to create the standard svn layout, for use with tools that require this (eg. git-svn). IMPORTANT: do NOT do an `svn up`. instead, re-use your working copy's existing files with `svn switch` (http://svnbook.red-bean.com/en/1.6/svn.ref.svn.c.switch.html).

units.py: convert(): Support ranges

Moved parse_range() from xml_func.py to units.py

units.py: conversions: Added ft->m conversion

units.py: MissingUnitsException: Fixed bug where quantity is a Quantity object, not a string, and thus needs to be converted to a string using strings.ustr()

units.py: convert(): Added support for unit conversions. Added initial unit conversion for % -> unitless. str2quantity(): Fixed regexp to match % as units. Set Quantity.__repr__ to quantity2str.

units.py: convert(): Put "units None" test after "quantity.units units" test because a destination of no units might require a conversion for some input units (e.g. % -> unitless requires a division by 100)

units.py: convert(): raise MissingUnitsException if quantity doesn't have units. MissingUnitsException: Take Quantity input instead of str.

units.py: Restructured to use a Quantity object for the units-tagged value and conversion functions quantity2str() and str2quantity() to convert between that and a raw string. Added convert() with basic support for removing units and passing through matching units. xml_func.py: _units: Added "to" attr. VegBIEN mappings: Remove units using new _units "to" attr instead of temporary workaround in _units.

Moved units-related functions from format.py to new units.py