Dodo Nethub support (#445)

* added support for XNS networking via Dodo-Nethub

* NetHub connection now optional (only if -nh-host is given); released NetHub-related changes to 'ether.c' to the public domain

* Added file using-dodo-networking-with-maiko.md

Documentation for building and using the Dodo-networking addition to Maiko

* Added support for running Maiko unter cygwin/x86_64-x

* Migrate Addr68k/NativeAlignment{2,4} in Nethub code, move timer/async defines to platform.h

* added missing include <netinet/in.h> for FreeBSD

* updated 'compile-flags' with added flags

* splitted ether.c in 3 (_common, _sunos, _nethub)

* reworks/modifications for nbriggs' pull-request review comments

* addintional additions for nbriggs' pull-request review comments

* get the Lisp packet lengths with 'LispInt2CInt'

* renamed variables in dblwordsSwap to indicate it's about double-words

* fixed wrong preprocessor directive unnoticed by clang

* added networking choice option to cmake build, fix to printf warning

- for cmake specify the networking to use with -DMAIKO_NETWORK_TYPE=<type>
- with <type> one of: NONE, SUN_DLPI, SUN_NIT, NETHUB
- e.g.: cmake .. -DMAIKO_NETWORK_TYPE=NETHUB

* integrated improvement to sendPacket() proposed by nbriggs

* integrated fix for SIGBUS on 32-bit big-endian, provided by nbriggs

* MAIKO_ENABLE_ETHERNET should not be unconditionally set on Solaris systems

* Receiving an ethernet packet is an ether interrupt but not an i/o interrupt.

Co-authored-by: dev hawala <devhawala@x.y>
Co-authored-by: Nick Briggs <nicholas.h.briggs@gmail.com>

src/initsout.c

@@ -46,7 +46,7 @@
 #include "mkcelldefs.h"    // for N_OP_createcell
 #include "testtooldefs.h"  // for MakeAtom68k, MAKEATOM
 
-#ifdef MAIKO_ENABLE_ETHERNET
+#if defined(MAIKO_ENABLE_ETHERNET) || defined(MAIKO_ENABLE_NETHUB)
 #include "etherdefs.h"
 #endif
 
@@ -117,9 +117,9 @@ void init_ifpage(int sysout_size) {
     Initialize IFPAGE
    */
   InterfacePage->machinetype = KATANA; /* 3 is katana */
-#ifdef MAIKO_ENABLE_ETHERNET
+#if defined(MAIKO_ENABLE_ETHERNET) || defined(MAIKO_ENABLE_NETHUB)
   init_ifpage_ether(); /* store ethernet ID in IF page */
-#endif /* MAIKO_ENABLE_ETHERNET */
+#endif /* MAIKO_ENABLE_ETHERNET or MAIKO_ENABLE_NETHUB */
   /*InterfacePage->dl24bitaddressable = (sysout_size == 32? 0xffff : 0);*/
   InterfacePage->dl24bitaddressable = (sysout_size == 8 ? 0 : 0xffff);
   new_lastvmem = (sysout_size * PAGES_IN_MBYTE) - 1;