Asymmetry in precedence predicates

[rjyounes]

gist defines:

• precedes
• directlyPrecedes, sub-property of precedes and inverse of directlyPrecededBy

gist does not define:

• precededBy

Shouldn't it define either both inverses or neither?

[rjyounes]

Closing: will be included in the general discussion of inverses in issue #506.