Named ranges bug

1) Debug print statement seems to be left in namedrange.py

2) Bug in parsing named ranges:

VLOOKUP(Country!$E$3, Table_Currencies[#All], 2, 9) True
Traceback (most recent call last):
.....
  File "/.../openpyxl-1.5.8-py2.6.egg/openpyxl/reader/excel.py", line 138, in _load_workbook
    wb._named_ranges = read_named_ranges(archive.read(ARC_WORKBOOK), wb)
  File "/.../openpyxl-1.5.8-py2.6.egg/openpyxl/reader/workbook.py", line 122, in read_named_ranges
    destinations = split_named_range(name_node.text)
  File "/.../openpyxl-1.5.8-py2.6.egg/openpyxl/namedrange.py", line 75, in split_named_range
    raise NamedRangeException('Invalid named range string: "%s"' % range_string)
openpyxl.shared.exc.NamedRangeException: Invalid named range string: " Table_Currencies[#All]"

Add tests for treating formulae as constants. Resolves #120, #168

→ <<cset f9996531db00>>