Call get-or-creaty-property-task instead of just get-property-task
fail after storing properties; this allows us to store multiple
properties in different rules
fixed broken library imports
fix http://yellowgrass.org/issue/NaBL/77
create <property>-task strategy (issue #76)
prefer PropertyConstraint over RefPropertyConstraint
support for @ in patterns
support for qualities (properties w/o values)
Revert "support for qualities (properties w/o values)"

This reverts commit 13082574147876c7d971e2c1de3ae6b6025a573d.
Revert "Revert "support for qualities (properties w/o values)""

This reverts commit d9bd6a29fdd9cca1c979fd0b177d753db497cac2.
new syntax for qualities
Fix wrong imports.
add origin-track-forced in congruences
nabl-def-site and nabl-external-def-site now take same term arguments

fixes http://yellowgrass.org/issue/NaBL/86
use different variable name for def-uri and uris which are passed around
pass implicits to nabl-external-def-site
make "defines in" work for implicit definitions; should also fix issues
with cases where the name comes after the subterm it is defined in
adding forced origin tracking does no longer destroy NoAnnoList terms
apply replacements to the name of refers to constraints
follow restrictions for keywords