Add Typesafe CLA to readme
Update link to sbt in readme
Fix zinc rebase implementation.

The old implementation returned None if the source file didn't
actually exist on the filesystem, and also if there was no matching
rebaser for the source file.

Since we only want to rebase files underneath the given bases, and
we don't need to support relativizing paths with ../ etc., we use an
efficient and naive prefix-matching algorithm, instead of analyzing
path segments.

Conflicts:
	src/main/scala/com/typesafe/zinc/SbtAnalysis.scala
Allow -output-relations and -output-products outside the context of compilation.

This is useful for dumping that data from existing analysis files without having
to compile (e.g., if the sources have changed, so a compile would change
the outputs).

This has turned out to be useful for debugging.
Update to scala 2.10 (for latest sbt 0.13)
Update scala 2.10 tests to 2.10.0
Add flag to mirror the analysis cache as text.

When working with zinc in a non-java based builder, it is useful to be able to
look at the same analysis cache being used by the compiler.  The current
"printRelations" flag requests that a compilation emits a textual
version of the cache. For compilation, this is adequate.  However, after
compilation, we frequently need to manipulate the analysis cache, doing merges
and splits to have analysis caches that match the build system's compilation
groupings.

In order to enable us to have a textual cache in sync with the
merged/split/rebased cache, in this change, I've added an option to the analysis
manipulation commands, "-mirror-cache-as-text".  When this flag is specified, a
readable text ".relations" file is generated, side-by-side with the original cache.

In order to test this, the change also adds a command to scriptit to check that
a particular file does not exists.  This allowed me to write tests that
verified that the text mirror files were only generated when the option was
passed.

Conflicts:
	src/main/scala/com/typesafe/zinc/SbtAnalysis.scala
Fixing review issues.

- Changed option name from "-mirror-cache-as-text" to "-mirror-analysis".
- Modified compile so that compilation also generates the mirrored text analysis file.
- Got rid of unnecessary "notexists" test command.

Conflicts:
	src/main/scala/com/typesafe/zinc/Compiler.scala
	src/main/scala/com/typesafe/zinc/SbtAnalysis.scala