Improvements to layout rule

[yav]

The current layout algorithm rejects the following program:

module A where
private
z = 0x2

with this error:

Parse error at test.cry:3:2,
  unexpected: layout block separator
  expected: a declaration

The issue is that after private we need to do 2 things: start a new block at the next token (because of private) or insert ; because z is on the indentation block start by where. Currently we seem to be preferring the latter, but I think we should prioritize starting a new block, before inserting a ;

[yav]

This should be fixed now