Fixed restrictions by empty AndLists and OrLists.

[dimitri-yatsenko]

Restrictions by AndLists and OrLists now work correctly

• rel & [] is equivalent to rel & dj.OrList()
• rel & [] produces the empty relation
• rel - [] has no effect
• rel & dj.AndList((cond1, cond2)) is equivalent to rel & cond1 & cond2
• rel & dj.AndList() has no effect
• rel - dj.AndList() produces the empty relation

Also, rel.restriction is now of type dj.AndList.

Also, RelationalOperand.project has been renamed to RelationalOperand.proj (issue #202) with project aliased to proj for backward compatibility.

[coveralls]

Coverage decreased (-0.1%) to 75.487% when pulling eea92aa on dimitri-yatsenko:master into ddad752 on datajoint:master.

[coveralls]

Coverage decreased (-0.05%) to 75.575% when pulling b141106 on dimitri-yatsenko:master into ddad752 on datajoint:master.

[eywalker]

Looks good :)