* device/include/pic16/pic18f2450.h,

* device/include/pic16/pic18f2450.h,
  device/include/pic16/pic18f4450.h,
  device/lib/pic16/libdev/pic18f2450.c,
  device/lib/pic16/libdev/pic18f4450.c,
  device/include/pic16/adc.h,
  device/include/pic16/pic16devices.txt,
  device/include/pic16/pic18fregs.h,
  device/lib/pic16/libdev/Makefile.am,
  device/lib/pic16/libdev/Makefile.in,
  device/lib/pic16/libio/Makefile.am,
  device/lib/pic16/libio/Makefile.in,
  device/lib/pic16/pics.all: added 18f2450 and 18f4450, closes #1844525

* device/lib/pic16/libsdcc/stack/stack.S: there is no need to pin the
  stack to a fixed location, relax it to automatically work with all
  but the smallest devices (256 byte RAM devices need #pragma stack)

git-svn-id: https://sdcc.svn.sourceforge.net/svnroot/sdcc/trunk/sdcc@5251 4a8a32a2-be11-0410-ad9d-d568d2c75423