Updated version to 2.3.0; Beginning of development of the next major version

- the contents are still the same as in 2.2.2, but patches will follow...
Moved and renamed rule files

- All rule files were moved:
  accel, emulate, nomap, simple and tools were moved from
  lua_scripts/pathmaps/* to modes/*

- devel, install and maemo_simple modes were moved to unsupported/modes/*,
  these modes will not be maintained now (maybe later during development
  of version 2.2, but not now)
Rules moved to "modes/*" and split to separate exec/fs rulefiles

* Changes to lua scripts and "sb2":
- fs rules are now in modes/*/fs_rules.lua, these are loaded always
- exec rules are in modes/*/exec_rules.lua, loaded only if needed
- exec_config.lua is loaded only if needed (was loaded always)
- FS rules refer to exec rules by name (exec_policy_name field)
- Rule file interface version == 100
- accel, emulate, tools, nomap and simple modes have been updated

* version set to 2.3development1
modes/*/exec_rules: Added.

- This commit adds exec rules for supported modes (these rules
  were separated from modes/*/fs_rules by the previous commit)
modeconf/sb2rc.* => modes/*/sb2rc
modeconf/host-*-packages.* => modes/*/host-*-packages
modeconf/gcc* => modes/*/gcc*
removed directory "modeconf"
Updaed debian/scratchbox2.postinst
More lua_scripts/pathmaps => modes changes
Added "binary_name" condition to rules (this commit: changes to the rule engine)
"emulate" mode: pwd_chain was replaced

- a new "binary_name" conditional rule was added to the rootdir
  rules, this obsoleted pwd_chain
"emulate" mode: Reorganized rules
"emulate" mode: dpkg_chain was replaced
"simple": no more qemu_chain, replaced that with simpler binary_name rules
"nomap": use "force_orig_path" instead of "use_orig_path"
modes/accel/fs_rules.lua: Added "name" field to some rules
No more chains in mapping rulesets, just plain rules

- The "chains" had become a redundant, unnecessary, extra layer on
  top of the the rule lists/trees. Code is simpler without them,
  and probably also slightly faster.
"emulate": Fixed a typo, added a comment

- fixed an earlier accident: removed an extra }
Union directories, prototype implementation (vrs 3)