Add macro files for new contexts (AlternateDecimals, AlternateIntervals, InequalitySetBuilder, Partition, Permutation, Root).
Fix alternate intervals so it works with answer checking (not sure wy this wasn't included initially.
Fix an infinite loop when checking sets formed by unions (using 'or'), and make empty sets print better.
Fix problems with AlternateDecimal context.

* fix cmp_defaults call that was throwing an error
* fix problem with spurious error messages due to
  results of computations being tested for decimal
  values when enterDecimals is ",".
* make values display properly according to the
  displayDecimal setting in more situations.
Fix output of alternate decimals in formula output.
Fix typo in InequalitySetBuilder documentation
Fix Permutation context to allow powers with parentheses.
Also, disallow unary plus for numbers, and prevent (2-3) from being
interpreted as (2 -3).  (It now produces an error message.)
Allow root() in complex contexts, and handle roots of negative numbers better.
Promotion of negative real shouldn't happen until evaluation (since we don't know if the result is actually negative or not when it is a formula).
Add Enable and Default functions to AlternateIntervals, and move initialization to a separate Init function for AlternateDecimals.
Make cmpDefaults work for limiting the type of interval that can be entered, and add the InequalitySetBuilder classes, since they aren't part of the default Interval context.
Fix up documentation for setting AlternateIntervals as the default.
Fix problems with negative powers and parentheses reported by Goeff.
Merge pull request #141 from dpvc/feature-new-macros

Add macro files for new contexts.