Fixed lapses in script generation

* Added support for search path to getexp (amends r3166)
* Added support for keyword substitution to default environment (amends r3061)

getexp

@@ -11,7 +11,9 @@ import sys
 from expconfig import ExpConfig, ExpConfigError
 from feedback import die
 
-# Utilities
+# Basic settings
+
+config_roots = os.environ.get('MKEXP_PATH', '').split(':')
 
 #
 # Main routine
@@ -44,7 +46,8 @@ if os.environ.has_key('DIFF'):
 
 try:
     config = ExpConfig(experiment_config_name,
-                       dict(map(lambda x: x.split('=', 1), sys.argv)))
+                       dict(map(lambda x: x.split('=', 1), sys.argv)),
+                       config_roots)
 except ExpConfigError as error:
     die(error.message, 2)