v3.01:
* Added `obj2' output format for OS/2
- Default attributes for a segment are ALIGN=16 and USE32.
- Add a segment to FLAT group implicitly if 32-bit segment.
- Recognize Unix sections .text, .rodata, .data and .bss as TEXT32,
CONST32, DATA32 and BSS32 respectively for compatibility with other
Unix platforms.
- Set default classes implicitly for known segments such as TEXT32,
CONST32, DATA32, BSS32 and so on.
* Changed `GROUP' directive to be cumulative
* Improved misc.