r15009 - gnucash/trunk/src - Allow budget values to default to unset, rather than zero.

[Chris Shoemaker]

Author: chris
Date: 2006-10-11 16:55:20 -0400 (Wed, 11 Oct 2006)
New Revision: 15009
Trac: http://svn.gnucash.org/trac/changeset/15009

Modified:
   gnucash/trunk/src/engine/gnc-budget.c
   gnucash/trunk/src/engine/gnc-budget.h
   gnucash/trunk/src/engine/gw-engine-spec.scm
   gnucash/trunk/src/gnome/gnc-plugin-page-budget.c
   gnucash/trunk/src/report/standard-reports/budget.scm
Log:
Allow budget values to default to unset, rather than zero.

Main patch by Gregory Alexander <gregalexa at gmail.com>.
On editing, interpret a blank as an unset budget value.
On reporting, show "." for unset budget values.
Add bugdet functions for testing whether a budget value is set or not, 
and for unsetting it.