ex7/PCA -> projectData.m and recoverData.m vectorized

[egoistpizza]

Updated two of the graded assignments in the PCA section of the ex7 exercise, projectData.m and recoverData.m.
The for-loops used to assign the Z and X_rec variables have been converted to non-iterative vectorized matrix multiplication single-line codes.

Before -> After (projectData.m)

% Before

for i = 1: size(X, 1)
  Z(i, :) = (U_reduce'*X(i, :)')';
end

% After

Z = (U_reduce' * X')';

Before -> After (recoverData.m)

% Before

for i = 1:size(Z, 1)
  X_rec(i, :) = (U_reduce*Z(i, :)')';
end

% After

X_rec = (U_reduce*Z')';