Aperture Macro - Correctly read subtraction operations and evaluations

[gowthamvbhat]

The recent update in EasyEDA software exports aperture macros with non-evaluated subtraction operations.

Example-

%AMMACRO1*1,1,$1,$2,$3*1,1,$1,$4,$5*1,1,$1,0-$2,0-$3*1,1,$1,0-$4,0-$5*20,1,$1,$2,$3,$4,$5,0*20,1,$1,$4,$5,0-$2,0-$3,0*20,1,$1,0-$2,0-$3,0-$4,0-$5,0*20,1,$1,0-$4,0-$5,$2,$3,0*4,1,4,$2,$3,$4,$5,0-$2,0-$3,0-$4,0-$5,$2,$3,0*%
%ADD11MACRO1,0.1016X-0.7874X-0.85X-0.7874X0.85*%

The AM statement reader assumed the negative operations would be pre-evaluated and the command would contain only unary negative values. In the above example, operation 0-$2 was being read as 0, $2

[rusefillc]

@curtacircuitos poke :)

[rusefillc]

see see #228