Add NASM-compatible multi-section binary support to bin object format.

Add NASM-compatible multi-section binary support to bin object format.
This allows for arbitrary load (LMA) and execution (VMA) addresses.

The following new section attributes are supported:
 - start (LMA start address)
 - follows (follow another section's last LMA)
 - align (LMA alignment)
 - vstart (VMA start address)
 - vfollows (follow another section's last VMA)
 - valign (VMA alignment)
In addition, sections can be designed progbits or nobits.

The following special symbols are generated for program use:
 - section.<sectname>.start (LMA start address)
 - section.<sectname>.vstart (VMA start address)
 - section.<sectname>.length (section length)

The ORG directive adjusts the file offset relative to LMA, so that if
ORG=0x100, a section with LMA=0x100 will be at file offset 0.

VMA addresses are the same as LMA addresses unless otherwise specified.

Full map file support is supported via the [MAP] directive.  The map output
filename can be set either as a parameter to the [MAP] directive or on the
command line with --mapfile=<filename>.  MAP options are BRIEF, SECTIONS,
SEGMENTS, SYMBOLS, and ALL (all of the above).  If no filename is specified
either on the command line or in the source file, the map is output to
standard output.

Full documentation will be added to the Yasm manual in the near future.

This implementation supports several configurations NASM does not, for
instance http://osdir.com/ml/lang.nasm.devel/2004-12/msg00032.html .
It is also fully 64-bit aware.

Fixes: #71, #99.
svn path=/trunk/yasm/; revision=2010