Added more input validation
- Improvement: added check for situation where -xmx  value < -xms value
Refactored input processing
Added --gui and --splash
- New Feature: user can now specify whether they want a native gui executable (non-blocking on command line, returns no input to command line) or native console executable (blocking on command line, returns input to command line)
- New Feature: user can now specify a splash screen image (in .bmp format) that will be displayed before a native gui executable is launched (only respected when the '--gui' flag is present)