* Convert all tabs to spaces.

        * src/Makefile.am: Add bapblockrect.cpp, bapblockrect.h,
        baplevelset.cpp, baplevelset.h, bapwidget.cpp, and bapwidget.h to
        editor sources. Remove baplevelsettabs.cpp and baplevelsettabs.h
        * src/bapbasics.cpp: Modify to use BAPLevelset instead of bap_levelset_t
        * src/bapbasics.h: Likewise.
        * src/bapblockrect.cpp: New file. Implements a stored version of a
        scheme (block-rect) command and its parameters, which can draw itself
        and tell if a point is inside of it.
        * src/bapblockrect.h: Likewise.
        * src/bapfield.cpp (BAPField): Load the skin, the current background,
        and the current blocks image. Connect the button press signal to
        BAPField::button_press
        * src/bapfield.cpp (load_background): New function for loading the
        current background using a BAPLevelParser to find out what it is.
        * src/bapfield.cpp (button_press): New function. If the user clicked
        on the usable field area, check if it's inside any widgets that are
        in the current level. If so, select it.
        * src/bapfield.cpp (draw): Don't call draw_blocks but instead just
        loop through the widgets in the levelset and draw each one that's in
        the current level.
        * src/bapfield.cpp (draw_block_rects): Removed.
        * src/bapfield.cpp (update): Load the background image.
        * src/bapfield.h: New local variables 'selected', a pointer to the
        selected widget, skin_surface, background_surface, and blocks_surface.
        New functions button_press and load_background.
        * src/baplevelloader.cpp: Use BAPLevelset instead of bap_levelset_t.
        * src/baplevelloader.h: Likewise.
        * src/baplevelparser.cpp (set_form): Don't use i to set the chunk but
        index instead.
        * src/baplevelparser.h: New function get_chunk_index.
        * src/baplevels.cpp: Use BAPLevelset instead of bap_levelset_t.
        * src/baplevels.h: Likewise.
        * src/baplevelset.cpp: New file implementing class BAPLevelset which
        represents a levelset.
        * src/baplevelset.h: Likewise.
        * src/baplevelsettabs.cpp: Removed.
        * src/baplevelsettabs.h: Likewise.
        * src/bapvarentry.cpp: Use BAPLevelset instead of bap_levelset_t.
        * src/bapvarentry.h: Likewise.
        * src/bapwidget.cpp: New file implementing class BAPWidget which
        represents some chunk of scheme code which generally will represent
        something graphical that the user can edit.
        * src/bapwidget.h: Likewise.
        * src/bapwindow.cpp: Use BAPLevelset instead of bap_levelset_t.
        * src/bapwindow.h: Likewise.