Known Issues:

 - (source path="true") printed as source=(path "true")
	Changes in pair syntax:
		x = y
	parsed as
		(x \= y)
			^
			a symbol with '=' as its content

 - It is not possible to encode an empty symbol
	Solutions:
		\e , as in "epsilon" for empty symbol
		\$ , as in regular expression

 - Symbol '=' is special in pairs
	Not a big issue, mostly affects pretty printing.

 - Newline encoding in multiline strings / comments
	Analyze string contents and only print it as a multiline
	if all newlines match output's newline sequence.

 - It is not possible to encode empty multiline comments
 - Multiline comments starting with = or \ are ugly
	Reserve characters {} and use them for the comments
	Remove single line comments

	Comments are:
		{...}
		{{...}}
		{{{...}}}
		...
	If there is a whitespace immediately after the last {, it is consumed as part of the
	'start comment' token.
	If there is a whitespace immediately before the first }, it is consumed as part of the
	'end comment' token.