* src/pic16/gen.c: fixed bug #1106975,

* src/pic16/gen.c: fixed bug #1106975,
* src/pic16/gen.c: fixed possible bug #1102572, now during TOS
pointer update, INTCON is saved, global interrupts are disabled and
restored after updateing TOS.
* src/SDCC.y, src/SDCC.lex, src/SDCCsymt.c, src/SDCCsymt.h:
* added function attribute 'shadowregs' to take advantage of shadow
registers,
* added function attribute 'wparam' as an alternative to the wparam
pragma,
* support/Utils/SDCCerr.[ch]: added error E_SHADOWREGS_NO_ISR when
user declares a non-ISR function as 'shadowregs',
* doc/sdccman.lyx: updated to reflect recent changes of pic16 port

git-svn-id: https://sdcc.svn.sourceforge.net/svnroot/sdcc/trunk/sdcc@3650 4a8a32a2-be11-0410-ad9d-d568d2c75423