Review request 6981484: Update development launcher

[Staffan Larsen]

http://cr.openjdk.java.net/~sla/6981484/webrev.00/

Update the development launcher (gamma) to 
  1) not require env.sh to be sourced before launching
  2) not require the current working directory to be the build directory
  3) exist on windows platforms as well
  4) support launching a debugger with -gdb/-gud (linux) or -dbx (solaris)

A few notes about the implementation:
- I did not change the current gamma launcher, but chose to add a new "frontend" to it called "fusion". This is a script that sets up the necessary environment. This was to avoid changing something that works.
- The launcher should really share code across platforms instead of being in os/<os>/launcher, but I wanted to keep the changes small.
- The launcher code for Windows is a copy of the launcher found in 6u22 with changes (#ifndef GAMMA)

Thanks,
/Staffan