Major changes

[Victorious3]

• Remove get_item and set_item, instead do it like scala where arr(n) gets the nth element. This means adding an update function.
• Allow juxtaposition of function arguments as top level expression: print "some string". This is related to the first point because it sidesteps an ambiguity with array indexing and literals.
• Rework struct initializers #36
• Add blocks (potentially evaluating to the last element)
• Add lambdas
• Remove the trailing colon in switch/case
• Add tuples
• change weak_ref to weak &