Missing proper XCore support

[wargio]

It seems that the current XCore support is quite lacking.

The output of the disassembler also does not follow the other archs as the branches/calls/jumps are always returned as relative.

Example:

|       .-> 0x00040344      entsp 2
|       :   0x00040346      getr  r0, 2
|       `=< 0x00040348      bt    r0, -2
|           0x0004034a      ldc   r0, 0x1e02
|           0x0004034e      ldw   r11, cp[0x34]
|           0x00040352      setd  res[r0], r11
|           0x00040354      outct res[r0], 1
|           0x00040356      testct r11, res[r0]
|       ,=< 0x00040358      bf    r11, 2
|       |   0x0004035a      chkct res[r0], 1
|       `-> 0x0004035c      outct res[r0], 1

Also seems that XS3 instructions are not supported.