* Split lib/default.nix into several files, as it had become a big

mess.  Also cleaned up some functions:

  - foldl appeared broken (it recursively called fold).
  - Renamed logicalAND/logicalOR to and/or.
  - Removed listOfListsToAttrs, eqStrings: obsolete.
  - Removed isInList, which does the same thing as elem.
  - stringToCharacters: don't return a "" at the end of the list.
  - Renamed concatList to concat, as concatList (singular) is a
    misnomer: it takes two lists.  Likewise, renamed mergeAttr to
    mergeAttrs.

  misc.nix still contains a lot of stuff that should be refactored and
  moved to other files.

svn path=/nixpkgs/trunk/; revision=14013

pkgs/lib/debug.nix

@@ -0,0 +1,15 @@
+rec {
+
+
+  # Wrapper aroung the primop `addErrorContext', which shouldn't used
+  # directly.  It evaluates and returns `val', but if an evaluation
+  # error occurs, the text in `msg' is added to the error context
+  # (stack trace) printed by Nix.
+  addErrorContext =
+    if builtins ? addErrorContext
+    then builtins.addErrorContext
+    else msg: val: val;
+
+
+
+}