simple-call-tree-sort-by-num-descendants

Rename sort-by-num-children to sort-by-num-descendants
and fix it so that it counts descendants at a given depth.
Also fix simple-call-tree-sort to let bind variable `invertedtree'
around call to sort predicate to indicate whether we are sorting
the inverted tree or the uninverted tree.
Also change some keybindings to reflect new names.

Altered items:
simple-call-tree-default-sort-method, simple-call-tree-mode,
simple-call-tree-set-priority, simple-call-tree-build-tree,
simple-call-tree-sort, simple-call-tree-count-descendants,
simple-call-tree-sort-by-num-children,
simple-call-tree-sort-by-num-descendants
New command simple-call-tree-goto-func

Altered items:
simple-call-tree-marked-items, simple-call-tree-get-attribs,
simple-call-tree-set-attribute, simple-call-tree-build-tree,
simple-call-tree-goto-func, simple-call-tree-jump-to-function,
simple-call-tree-mark
Basic marking commands, and a few fixes.

Also some keybinding changes.

Altered items:
hl-line, simple-call-tree-mode, simple-call-tree-mark-face,
simple-call-tree-get-function-at-point,
simple-call-tree-compare-items, simple-call-tree-goto-func,
simple-call-tree-toggle-narrowing, simple-call-tree-mark,
simple-call-tree-unmark, simple-call-tree-unmark-all,
simple-call-tree-outline-show, simple-call-tree-outline-hide, not