Rename Parallel->ConcurrentTag, introduce InOrderSequentialTag

See merge request inducer/loopy!164

Check that no new inames are added to instructions by ILP realization

See merge request inducer/loopy!162

project out local-id-mapped inames before domain comparison for barriers; solves #94 on gitlab

See merge request !159

Make sure Barvinok-based count() returns a PwQPolynomial of the right space

See merge request inducer/loopy!161

Implement an 'aliases_base_storage' property for TemporaryVariable

See merge request inducer/loopy!143

Arg shape fixes

See merge request inducer/loopy!158

Have reduction realization inherit predicates

See merge request !156

[bugfix] Avoid vanishing predicates

See merge request !157

whenever asked for something it does not do. This matches
the behaviour of the base class ASTBuilderBase.

Previously predicates, that could be hoisted up to a CallKernel
schedule item were silently dropped by the DummyHostASTBuilder.
This commit fixes the issue, by introducing a property whether
an AST builder is able to implement conditionals. If not so, the
hoisting of predicates is turned off (aka delayed until device
code is generated).

Use WriteOncePersistentDict instead of PersistentDict.

See merge request inducer/loopy!155

Add an identity check to LoopKernel.__eq__

See merge request inducer/loopy!154

This is going to make pytools!4 more useful, by avoiding expensive
checks for the in-memory cache.