added option (-T2) to order symbols by definition appearance in code

[thrust26]

By ordering the symbol according to their definition order in the code, the disassembling can be significantly improved.

Using their own, well defined symbols, the disassemblers and debuggers can group the symbol file. From that grouping, the type of a symbol can be identified (e.g. constant vs. variable). Also in bankswitched code (e.g. Atari 2600), the disassembler will know to which bank a label belongs.

Now:

BLUE = $80
...
var = $80
...
; bank0
LabelFromBank0
  lda BLUE          ; !!!
  lda #BLUE
  ...
; bank1
LabelFromBank0      ; !!!

Future:

DASM_CONSTS
BLUE = $80
...
DASM_ZP_VARS
var = $80
...
DASM_BANK_0
LabelFromBank0
  lda var           ; !!!
  lda #BLUE
  ...
DASM_BANK_1
LabelFromBank1      ; !!!

[dionoid]

Changes look good. I like the way this is implemented as new -T2 option, so there won't be compatibility issues.