Allow duplicate element names in MAD-X parser

[austin-hoover]

MAD-X allows a single element definition to be repeated in a LINE definition. For example:

SCH_B02: Sextupole, L=LSH2, K2:=KSH2;
BPM_B02: Monitor;
KDHTB2:=0.0;
DMCH_B02: HKICKER, L=0.0, KICK=KDHTB2;
QSC_B02: MULTIPOLE, KNL:={0,KSC_B02,0};
SSXC_B02: MULTIPOLE, KSL:={0,0,KSSB2_8};
QB2: Line = (DDMCH_X02, DMCH_B02, QSC_B02, SSXC_B02, DDMCH_X02a, BPM_B02, DDMCH_X02b, Q2U, BPM_B02, QTH_B02, Q2D, SCH_B02);

This will output:

...
ssxc_b02, at = 18.92687188;
bpm_b02, at = 19.11879438;
bpm_b02, at = 19.23008388;
qth_b02, at = 19.48008388;
...

When it is read by orbit.teapot.TEAPOT_Lattice, the parser ignores the repeated element. See the SNS AR example here:

sns-ring-madx.zip

MAD-X tunes are 6.23, 6.16, and lattice length is 248.0098418.

Old output:

{'Ekin [GeV]': 1.2999999999999996,
 'alpha x': 0.06789673569066759,
 'alpha y': 0.002402281876774005,
 'beta x [m]': 11.433116314710075,
 'beta y [m]': 15.056203017824776,
 'dispersion prime x': 0.005737171344151361,
 'dispersion prime y': 0.0,
 'dispersion x [m]': -0.12422795506639159,
 'dispersion y [m]': 0.0,
 'eta': -0.1388907500980499,
 'fractional tune x': 0.22590630069001874,
 'fractional tune y': 0.15526948263492443,
 'frequency [Hz]': 1097951.0103074508,
 'gamma transition': 5.2104862428362155,
 'gamma x [m^-1]': 0.0878684288088322,
 'gamma y [m^-1]': 0.06641819121157827,
 'mass [GeV]': 0.938272029,
 'momentum [GeV/c]': 2.0321189127115566,
 'momentum compaction': 0.03683354278126075,
 'period [sec]': 9.107874491776984e-07,
 'transition energy [GeV]': 3.9505814701425224}
length = 247.89855230430024

New output with the modified parser:

{'Ekin [GeV]': 1.2999999999999996,
 'alpha x': 0.04170263505574618,
 'alpha y': 0.03250788492204014,
 'beta x [m]': 11.484241377667265,
 'beta y [m]': 14.711577053277404,
 'dispersion prime x': 0.0029994494463154594,
 'dispersion prime y': 0.0,
 'dispersion x [m]': -0.09888446210253576,
 'dispersion y [m]': 0.0,
 'eta': -0.13892488592900948,
 'fractional tune x': 0.2301327537383606,
 'fractional tune y': 0.16037073821882294,
 'frequency [Hz]': 1097458.3265571904,
 'gamma transition': 5.212902355810395,
 'gamma x [m^-1]': 0.08722727754065196,
 'gamma y [m^-1]': 0.06804550993797799,
 'mass [GeV]': 0.938272029,
 'momentum [GeV/c]': 2.0321189127115566,
 'momentum compaction': 0.03679940695030118,
 'period [sec]': 9.111963304675772e-07,
 'transition energy [GeV]': 3.952848441365099}
length = 248.00984180430024

[austin-hoover]

Note: in this case there appears to be an error with the MADX lattice definition: BPM_B02 is repeated when defining the beam line. I'm not sure what the default PyORBIT behavior should be in this case. Should we allow duplicate element names?