The last piece of the subc "refdes text" cleanup is done. The new code 
fits nicely into the new data model and pcb-rnd's approach: instead of 
hardwired hacks and side effects that happen to do The Right Thing for 
one specific case, provide a few, orthogonal features that can be combined 
to do the same thing, or 100 other things.

<h1>Old, pcb-mainline model: "element text"</h1>
<p>
An element has 3 hardwired text objects that have to contain the refdes, 
the value and the footprint name. Further limitations:
<ul>
<li> all three element text object have to have the same coordinates and font 
and size

<li> they can be only on silk, and all three must be on the same silk layer

<li> special exception from under the element-lock: the only element-part 
you can move without moving the element is the element text (e.g. the only 
element part that can change its position compared to other parts of the 
element without breaking the element up first)

<li> and the element text can always be moved, you can't locally lock it 
to the element; so you can't have a special element where the text has a 
fixed position for whatever reason

<li> there was exactly 3 of these - no more, no less

<li> they could contain only what the programmer thought would be useful

<li> only one of them could be displayed at a time, and which one got 
displayed was a board-global setting; this global setting also affected 
some
</ul>

<h1>New, pcb-rnd subc model:</h1>
<p>
Instead of the bunch of hardwired properites and restrictions of an 
element text, subcircuits offer a set of orthogonal features that can be 
used to reproduce the behavior of element texts too, but can also be used 
more flexibly:
<ul>
<li> subcircuits consist of any object on any layer

<li> these objects can be text, and can be on a silk layer

<li> a text object can have the DYNTEXT flag, in which case the code does %% 
substitution on the text; e.g. if the text string 
contains %a.parent.refdes%, the part between the %% is substituted with 
the refdes attribute ("a.") of the parent subcircuit ("parent."). In 
short: it's replaced with the subcircuit's refdes

<li> there's no limitation on the number of text objects having DYNTEXT 
flags - you can have one displaying the refdes on silk, another on copper

<li> there's no limitation on what attribute is displayed; refdes, value and 
footprint name are not special any more, they are just attributes. You can 
introduce your own attributes, and you can get them printed in text

<li> with these, you can have a resistor footprint that prints both the 
refdes and the value on silk, side by side

<li> if any object of a subcircuit has the FLOATER flag, it can be moved 
within the subcircuit (and can be edited without breaking up the 
subcircuit); the "lock names" and "only names" became "lock floaters" and 
"only floaters".
</ul>

<h1>How to emulate the old behavior with the new features</h1>
<p>
To get a subc refdes that behaves the same as an element refdes text, 
except that it's only a refdes text and not a 3-fold "magic text":
<ul>
<li> on a silk layer create a text object that will be part of the subc

<li> set the text string to %a.parent.refdes% so that it will always display 
the subcircuit refdes

<li> edit flags to turn on DYNTEXT and FLOATER; the first lets pcb-rnd 
replace %% patterns, the second lets the user grab and move the text
</ul>
<p>
Note: when you convert buffer to subc and it doesn't have a refdes text, 
the code automatically adds one, so you don't need to do this manually for 
each new subcircuit you draw.