Bump scalaVersion to 2.11.2 in Build.scala

This commit finally gets Spire using 2.11 by default. The reason
we took so long getting here was all the warnings that our build
would spit out. This commit fixes all but 9 of the warnings.

Many warnings (unused imports, BigDecimal, etc) were dealt with
directly. However, there were a lot of deprecation warnings
involving macros where there was no obvious way to be compatible
with 2.10 but to ellide warnings in 2.11.

This commit solves the problem (well, mostly solves it) using
spire.macros.Compat, an object that contains methods implementing
the changed/deprecated methods (as well as a type alias for the
deprecated Context type). This means instead of hundreds of warnings
in the macros project, we now have 8, and we have 0 warnings
in core.

Sadly, there is still the persistent "Not a simple type" warning
as well.
Removed commented out code.

Thanks to @DRMacIver for keeping me honest.
bump travis version
Merge pull request #287 from non/topic/bump-to-211

Bump scalaVersion to 2.11.2 in Build.scala
Initial implementation of a three-valued logic type (Trilean).

The main objective is just to see how well this works using a value
class implementation (wrapping an Int). The representation is:

  0 = false   (all bits 0)
 -1 = true    (all bits 1)
  1 = unknown (last bit 1)

This might not be something that is generally-useful enough to include in
Spire. I just wanted to code it up and see how it looked.
Respond to @tixxit's review comments.
Some more small additions to Trilean.
Some possibly helpful methods involving Trileans
Merge pull request #288 from non/topic/trilean

Initial implementation of a three-valued logic type (Trilean).
Remove Ops macros in favor of Machinist.

Now that we are publishing the ops macros externally via Machinist,
it made sense to stop duplicating that code internally. Machinist
0.3.0 supports all the operator styles/names that Spire needs as
of now, and it will be easy to publish future changes as we need
them for Spire.

(We could also keep our own names map here, if we wanted to stop
relying on Machinist's DefaultOps class.)
Some README updates.
Update README documentation.
put a out-of-date warning in the GUIDE
add missing resolver
Setting version to 0.8.0
Setting version to 0.8.1-SNAPSHOT
disable scaladoc to allow release
Setting version to 0.8.1
Setting version to 0.8.2-SNAPSHOT
reenable scaladoc