Integration - "projects" report

- "projects" report converted to 1.8.0.
- Relocated code from task.cpp to recur.cpp to allow unit tests to link
  without includign task.cpp and therefore main.
- Removed obsolete sandbox directory.
- Fixed bug where Config::load deleted the pre-loaded custom reports.
- Fixed bug where Cmd::valid failed to include custom reports properly.

src/Makefile.am

@@ -4,7 +4,7 @@ task_SOURCES = Config.cpp Date.cpp Record.cpp T.cpp T2.cpp TDB.cpp TDB2.cpp   \
                Duration.cpp StringTable.cpp Location.cpp Subst.cpp Keymap.cpp \
                Nibbler.cpp Context.cpp Cmd.cpp color.cpp parse.cpp task.cpp   \
                edit.cpp command.cpp report.cpp util.cpp text.cpp rules.cpp    \
-               import.cpp interactive.cpp                                     \
+               import.cpp interactive.cpp recur.cpp                           \
                Config.h Date.h Record.h T.h TDB.h Att.h Filter.h Sequence.h   \
                Table.h Grid.h Timer.h Duration.h StringTable.h Location.h     \
                Subst.h Keymap.h Nibbler.h Context.h Cmd.h color.h task.h