WIP: Start renaming imagej.ops.map package

We discussed how to do naming of ops in general.

- imagej.ops.foo where "foo" is the operation's name
- "Foo" is base interface for that type of op
- imagej.ops.foo.bar to group all "bar" ops (still named "foo")
 -- "Bar" interface extends "Foo"
 -- All ops in imagej.ops.foo.bar implement Bar
- parallel ops are prefixed with "Parallel"
 -- if we later judge this too long, we'll reconsider

To represent inputs and outputs, we use notation:
- FooABC2XYZ
 -- Where A, B, C, X, Y, Z are letter codes
 -- Inputs left of the "2", outputs right of it
- Codes:
 - I = Iterable (e.g., IterableInterval)
 - R = RandomAccessible (e.g., RandomAccessibleInterval)
 - N = number (e.g., NumericType)
 - Img = Img & ImgPlus
Merge branch 'master' into rename-maps

Conflicts:
	src/main/java/imagej/ops/map/Map.java
	src/main/java/imagej/ops/map/MapI2I.java
	src/main/java/imagej/ops/map/ParallelMap.java
	src/test/java/imagej/ops/join/JoinTest.java
Refactored Map and subclasses to new naming schema
Loops: Code-Cleanup
Merge branch 'master' of https://github.com/imagej/imagej-ops