There's a utility in the contrib directory called mapmapper which
converts old style maps (1.x) to new style maps (2.x).

The new map format is as follows:

	SYMBOL			MEANING

	x			Completely filled block
	s			Upper left half filled
	w			Lower left half filled
	q			Lower right half filled
	a			Upper right half filled

	b			Completely filled decoration block
	h			Upper left half filled
	y			Lower left half filled
	t			Lower right half filled
	g			Upper right half filled

	#			Fuel block

	r			Upwards cannon
	d			Leftwards cannon
	f			Rightwards cannon
	c			Downwards cannon

	_			Neutral base
	0..9			Base belonging to team n
	*			Treasure (belongs to team with closest base)
	!			Target (belongs to team with closest base)

	+, -			Positive/repelling and negative/attracting grav
	>, <			Clockwise and anti-clockwise grav
	i			Upwards gravity current
	j			Leftwards gravity current
	k			Rightwards gravity current
	m			Downwards gravity current

	@, (, )			In/out, in and out wormholes respectively

	A..Z			Checks, 'A' = start

	$			Force the direction of homebases.
				Players starting on homebases that are
				adjacent to this symbol will start with the
				front of their ship pointing to this dollar
				sign.  Clients don't draw this symbol.

	%			Item concentrator.  Putting it in a map will
				determine where items appear.  When one or more
				item concentrators are in a map then
				itemConcentratorProb (1.0 by default) of all
				items appear only in an area around the item
				concentrators; the remainder of the items, or
				all of them if no item concentrators are
				defined, popup anywhere.  The area is a circle
				with a radius determined by the server option
				-itemConcentratorRadius.  An item concentrator
				is drawn on screen as three rotating triangles.

	z			Friction block.  Ships in this kind of block
				have friction acting on them equal to
				blockFriction, not friction.  The option
				blockFrictionVisible determines whether
				or not players see the friction block as
				decor or not at all.

	^			Empty Treasure.  Belongs to the team with
				closest base.  An empty treasure behaves
				like a regular treasure, except that it
				does not own a ball.

	any other char		Empty block

	elnopuv~`&=[]{}|:;"',.?/ are free for future expansion.

In case you are wondering if all the characters for map symbols have any
special meaning, they are not abbreviations, but if you take a look at
where they are placed on the keyboard, you might grasp the logic behind
selecting them.  Try imagining the block center between the keys qwas
(for the logica behind qwas) and between dfrc (for the logic behind dfrc).
'x' was just chosen since it makes a nice 'fill it all' character.