tweaked MaSh features, based on comments by Josef Urban

increase weight of local facts again (MaSh)

simplify code now that "mash.py" supports weights

added weights to MaSh (by Daniel Kuehlwein)

Move the measurability prover to its own file

Show search depth in the debug output of the measurability prover

Remove looping rule from measurability prover

rules for improper Lebesgue integrals (using tendsto at_top)

take proximity into account for MaSh + fix a debilitating bug in feature generation

tuning

clarified default button (cf. org/gjt/sp/jedit/gui/OptionsDialog.java);

select logic session names, not paths;

added keyboard shortcut for button (canonical way to do that?);

evade ugly default font, notably on Windows laf;

center main window;

more direct dialog via existing GUI components;

clarified logic argument: session name, not path name; tuned;

tuned message;

implicit build_dialog for Isabelle/jEdit; clarified option -l: refer to session name, not image path;

tuned message;

tuned OK feedback;

check for existing image (even if outdated); removed conflicting "clean" option;

more elementary dialog, with less interaction;

basic interaction with build process;