Added and completed some instructions to work with stack(dup, dup_x1, dup_x2, dup2, dup2_x1, dup_x2, swap, pop, pop2). Added boolean field hasDoubleSize for Expression and initialized in every constructor Expression's
inheritors (in BinaryExpression, Constant, etc)
merged with zabranskiy/djlab
Merge pull request #9 from Podmev/master

Added and completed some instructions to work with stack(dup, dup_x1, du...