Code Cleanup

- Eliminated valid.cpp by relocating functions to more sensible locations.

src/Makefile.am

@@ -3,8 +3,8 @@ task_SOURCES = Att.cpp Cmd.cpp Config.cpp Context.cpp Date.cpp Duration.cpp   \
                Filter.cpp Grid.cpp Keymap.cpp Location.cpp Nibbler.cpp        \
                Record.cpp Sequence.cpp StringTable.cpp Subst.cpp Task.cpp     \
                TDB.cpp Table.cpp Timer.cpp Permission.cpp color.cpp edit.cpp  \
-               command.cpp import.cpp interactive.cpp valid.cpp recur.cpp     \
-               report.cpp custom.cpp rules.cpp main.cpp text.cpp util.cpp     \
+               command.cpp import.cpp interactive.cpp recur.cpp report.cpp    \
+               custom.cpp rules.cpp main.cpp text.cpp util.cpp                \
                Att.h Cmd.h Config.h Context.h Date.h Duration.h Filter.h      \
                Grid.h Keymap.h Location.h Nibbler.h Record.h Sequence.h       \
                StringTable.h Subst.h Task.h TDB.h Table.h Timer.h             \