Renames IsSetBefore into IsSetWithin, to follow comments from https://github.com/tpierrain/NFluent/issues/107
Updates the release note to include Cyrille's bug fix.

Improves the UserReportedIssuesTests.SpuriousExceptionOnError() test by indicating the Expected error message.
Fixes Cyrille's pull request StyleCop issues (including usage of tabs instead of spaces).
Makes TimeUnit as mandatory parameter for EventWaitHandle checks.
Introduces a Duration.ConvertToMilliseconds static method.
Moves duration checks into the new Duration tests fixture, and replaces previous NUnit Assertions with Checks for it.
Updates the backlog file.
Adds IsNaN() check for double and creates T4 that is cloning double for float.
Updates T4 so that the FloatFloatingPointBinaryRelatedTests file is properly generated.
Adds the IsFinite() check. ( https://github.com/tpierrain/NFluent/issues/110 )
Fixes the release note.
Sets the proper PCL value within the nuspec and the ReleaseNote files.
Resets version number and release note (after yesterday release of 1.2).