Hide the logic for command resolution for commands, aliases & user commands behind a single
interface so everybody does it the same way.  Add an "exact" lookup for internal uses.

Fix up a few little cases where we weren't reporting command lookup errors correctly.

Added "b" as an alias for "breakpoint" so it doesn't collide with "bt".



git-svn-id: https://llvm.org/svn/llvm-project/llvdb/trunk@107718 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/source/Commands/CommandObjectAlias.cpp b/source/Commands/CommandObjectAlias.cpp
index 62ffbf4..5c09a2a 100644
--- a/source/Commands/CommandObjectAlias.cpp
+++ b/source/Commands/CommandObjectAlias.cpp
@@ -121,7 +121,7 @@
     }
     else
     {
-         CommandObjectSP command_obj_sp(interpreter.GetCommandSP (actual_command.c_str()));
+         CommandObjectSP command_obj_sp(interpreter.GetCommandSPExact (actual_command.c_str(), true));
          CommandObjectSP subcommand_obj_sp;
          bool use_subcommand = false;
          if (command_obj_sp.get())