Build: configuring via environment is bad practice

Yes, I know...
Programmers absolutely LOVE to sneak-in various nifty toggles via environment.

Yet this is an anti-pattern!
And, by extension of that verdict, a "build interface" which relies
on the implicit convention that some magical variables are set,
is **not a proper interface** but a hack.

Thus we abandon that bad practice and handle the build in a clean and explicit way.

 * the DEB-Build in `debian/rules` now invokes SCons explicitly, passing arguments
 * the Lumiera Build-System is FSH aware and knows the proper installation locations
 * the setup of the application uses a setup configuration, shipped with the package
 * there is no need to ''compile-in any configuration''
   ** `LUMIERA_PLUGIN_PATH` is obsolete and unused since several years now
   ** `LUMIERA_CONFIG_PATH` was never used at all
   ** consequently, we also do not need `PKGLIBDIR` and `PKGDATADIR`

admin/scons/Options.py

@@ -43,8 +43,6 @@ def defineCmdlineVariables(buildVars):
 #                   allowed_values=('auto', 'i386', 'i686', 'x86_64' ), ignorecase=2)
         ,PathVariable('PREFIX', 'Installation dir prefix', 'usr/local', PathVariable.PathAccept)
         ,PathVariable('INSTALLDIR', 'Root output directory for install. Final installation will happen in INSTALLDIR/PREFIX/... ', '/', PathVariable.PathAccept)
-        ,PathVariable('PKGLIBDIR', 'Installation dir for plugins, defaults to PREFIX/lib/lumiera/modules', '',PathVariable.PathAccept)
-        ,PathVariable('PKGDATADIR', 'Installation dir for default config, usually PREFIX/share/lumiera', '',PathVariable.PathAccept)
      )
 
 

admin/scons/Setup.py

@@ -82,11 +82,7 @@ def defineBuildEnvironment():
     appendVal(env,'OPTIMIZE', 'CCFLAGS',   val=' -O3')
     appendVal(env,'DEBUG',    'CCFLAGS',   val=' -ggdb')
     
-    # setup search path for Lumiera plugins
-    appendCppDefine(env,'PKGLIBDIR','LUMIERA_PLUGIN_PATH=\\"$PKGLIBDIR/:ORIGIN/modules\\"'
-                                   ,'LUMIERA_PLUGIN_PATH=\\"ORIGIN/modules\\"')
-    appendCppDefine(env,'PKGDATADIR','LUMIERA_CONFIG_PATH=\\"$PKGLIBDIR/:.\\"'
-                                    ,'LUMIERA_CONFIG_PATH=\\"$DESTDIR/share/lumiera/:.\\"')
+    # NOTE: could define optional copile features here....
     
     Options.prepareOptionsHelp(buildVars,env)
     buildVars.Save(OPTCACHE, env)