In new grammar:

- Removed explicit consumption of newline whitespace and added
requirement of colon after keywords. I.e., there is no longer a
requirement between a keyword and its proceeding first argument to only
consist non-newline-whitespace. 
Thus:

x:
y
A:
b

=>

(x: y A: b)

- Added support for chained unary message. E.g.:

x.unaryMessage.anotherUnaryMessage

- Added support for single arg/keyword message as arguments for multi
arg/keyword messages. Thus, for the following:

x: msg: arg Y: msg2: msg3: arg2

=>

x: (msg: arg) Y: (msg2: (msg3: arg2))

- Changed prefix for par-args from : to \.

Signed-off-by: Jakob Brandsborg Ehmsen <jakobehmsen.github@gmail.com>