Log Message:
update to 0.7.7
changes:
* Add IsPositiveDefinite, IsPositiveSemidefinite, QuarticFormula
* SEMANTICS: QuadraticFormula, CubicFormula, Eigenvalues, and DiagonalOf
  now consistently return a column vector
* Fix CubicFormula for complex coefficients and better handle real roots,
  and use QuarticFormula in PolynomialRoots
* Eigenvalues now computes eigenvalues for 3x3 and 4x4 matrices
-some UI improvements
* Documentation updates
* Fix plugin reading
* Portability fixes
* Translation updates