Find party slot for new unit

[0x001c6000] addiu r29,r29,-0x0020
[0x001c6004] sw r31,0x0018(r29)
[0x001c6008] sw r17,0x0014(r29)
[0x001c600c] jal 0x00180afc
[0x001c6010] sw r16,0x0010(r29)
[0x001c6014] lbu r2,0x0006(r2)
[0x001c6018] nop
[0x001c601c] andi r2,r2,0x0001
[0x001c6020] bne r2,r0,0x001c6088
[0x001c6024] ori r2,r0,0x0002
[0x001c6028] addu r16,r0,r0
[0x001c602c] ori r17,r0,0x00ff
[0x001c6030] jal 0x00059af0
[0x001c6034] addu r4,r16,r0
[0x001c6038] addu r5,r2,r0
[0x001c603c] lbu r2,0x0001(r5)
[0x001c6040] nop
[0x001c6044] beq r2,r17,0x001c6064
[0x001c6048] nop
[0x001c604c] lbu r2,0x0000(r5)
[0x001c6050] nop
[0x001c6054] beq r2,r0,0x001c6064
[0x001c6058] sltiu r2,r2,0x0004
[0x001c605c] bne r2,r0,0x001c6074
[0x001c6060] nop
[0x001c6064] addiu r16,r16,0x0001
[0x001c6068] slti r2,r16,0x0014
[0x001c606c] bne r2,r0,0x001c6030
[0x001c6070] nop
[0x001c6074] addu r4,r0,r0
[0x001c6078] jal 0x00059d5c
[0x001c607c] addiu r5,r5,0x0003
[0x001c6080] nor r2,r0,r2
[0x001c6084] sltu r2,r0,r2
[0x001c6088] lw r31,0x0018(r29)
[0x001c608c] lw r17,0x0014(r29)
[0x001c6090] lw r16,0x0010(r29)
[0x001c6094] addiu r29,r29,0x0020
[0x001c6098] jr r31
[0x001c609c] nop