improved pipeline/workflow rendertree node types and labels
Handle all wildcards (`{*}`, `[*]`, and `.*`).

* `{*}` requires map/reduce
* introduce `Splice` for wildcard projections
* `Wildcard` is replaced by `Splice(None)`
* `{*}` and `[*]` expand to the equivalent functions
* `namedProjections` doesn’t name flattening of the entire relation
Merge remote-tracking branch 'upstream/master' into ready/173-object-flatten

Conflicts:
	src/main/scala/slamdata/engine/compiler.scala
	src/main/scala/slamdata/engine/semantics.scala
	src/main/scala/slamdata/engine/sql/parser.scala
	src/test/scala/slamdata/engine/backend.scala
	src/test/scala/slamdata/engine/semantics.scala
exclude pending tests from coverage data

override pendingUntilFixed to not run pending tests if isCoverageRun is true

set isCoverageRun flag in travis/scoverage
fix infinite recursion when not in coverage mode
Merge pull request #328 from mossprescott/ready/pending

exclude pending tests from coverage data
load each data set only the first time it's used (Fixes #330)

also, do not include data set load time in the timing for each test
Update README.md
keep temp files separate and clean up only the correct ones (Fixes #305)

The regression spec and the filesystem spec were each deleting the
entire temp directory, which meant they could delete each other's files
depending on timing.

This should fix the intermittent failures we've been seeing.
Merge pull request #333 from mossprescott/ready/330

Integration test fixes
preserve order of projections in inlineProject
be sensitive to the order of fields when checking results

Note: only the order of fields in the top-level object is currently
checked. For example, that means the order of fields inside "value"
is not verified.

Produces a nice message if the fields are correct but out of order.

See #313, which this does not fix (more like makes it actually broken)
test simple select with more than 4 projections
Merge pull request #334 from mossprescott/ready/field-order

Check order of top-level fields in result
emit simple value for "Eq" selector
Instead of an undocumented $eq operator that may work only in mongo 2.6.
Merge pull request #335 from mossprescott/ready/simple-eq

Simplify Eq selectors
Decompose & coalesce MapReduceOps.

`MapReduceOp` has been replaced by `MapOp`, `FlatMapOp` and `ReduceOp`,
which are more atomic and composable. This also makes the `coalesce` and
`crush` methods on those operations more aggressive than the ones on
`MapReduceOp` were.

Fixes #271.

Also,

* fix a bug in `>>>` where it didn’t maintain the `base` properly and
* add integration tests for various map/reduce queries.
Merge remote-tracking branch 'upstream/master' into ready/271-coalesce-MapReduceOp
Merge pull request #318 from mossprescott/minor

improved pipeline/workflow rendertree node types and labels
Eliminate unused Traverse impl.