Fuse ops and save alloc in Fpf (prev FPFilter).

This replaces Fpfilter with a new tpye Fpf. This acts in a similar way,
but makes heavy use of macros to make it possible to completely avoid
allocations in the common case when doing sign tests on algebraic
expressions.
Rename Fpf => FpFilter.
Calculate ind at compile time when possible.
Move FpFilter to spire.math.
remove unnecessary sbt key
add reductum method to Polynomial
Add FpFilter benchmark.
Don't truncate BigDecimals without any context.
Update to 2.11.1.

This commit also removes code which used octal literals.
Setting version to 0.7.5
Add some property tests for orientation tests.
Setting version to 0.7.6-SNAPSHOT
Merge remote-tracking branch 'upstream/master' into topic/fpfilter-macros

Conflicts:
	tests/src/test/scala/spire/algebra/RingTest.scala
update readme to 0.7.5
Merge pull request #254 from tixxit/topic/fpfilter-macros

Floating Point Filter macro-fication