Changed semantics in parsing code

Reformated and changed naming of parsing structures to match
most languages. V is composed of two core components:

Expressions which result in direct or indirect values with side
affects occuring only in function calls:

    a + 2
    a >= '3'
    add(a, 2)
    [1,2,3] ++ 2
    if (a) 1 else 2
    while (time() < 3) 5
    for (i : 0..5) sqrt(i)

Statements which encapsulate any single syntactic structure of v:

    a + 2
    a = 3*a
    a = add(a, 3)
    print('hello')
    break
    while (true) print('hello')

All expressions can stand by themselves as statements.