Refactor: utilize callf where possible

Also new command simple-call-tree-mark-by-buffer
Complete export commands
Make start on simple-call-tree-move-item-up/down

Altered items:
ido, newcomment, simple-call-tree-mode, simple-call-tree-invert,
simple-call-tree-valid-face-p, simple-call-tree-next-func,
simple-call-tree-set-attribute, simple-call-tree-set-tags,
simple-call-tree-add-tags, simple-call-tree-build-tree,
simple-call-tree-list-callers-and-functions,
simple-call-tree-listed-items, simple-call-tree-export-org-tree,
simple-call-tree-export-items, simple-call-tree-insert-org-header,
simple-call-tree-get-parent, simple-call-tree-sort,
simple-call-tree-reverse, simple-call-tree-move-item-up,
simple-call-tree-move-item-down, simple-call-tree-invert-buffer,
simple-call-tree-move-up, simple-call-tree-move-top,
simple-call-tree-toggle-duplicates, simple-call-tree-unmark,
simple-call-tree-mark-by-priority, simple-call-tree-kill-marked
Fix simple-call-tree-move-item-up/down

Altered items:
simple-call-tree-mode, simple-call-tree-move-item-up,
simple-call-tree-move-item-down
Fixed org-export commands

Altered items:
simple-call-tree-export-org-tree, simple-call-tree-export-items,
simple-call-tree-insert-org-header
Speed optimizations

Altered items:
simple-call-tree-symbol-as-regexp, simple-call-tree-add,
simple-call-tree-analyze, simple-call-tree-invert,
simple-call-tree-valid-face-p, simple-call-tree-next-func,
simple-call-tree-build-tree,
simple-call-tree-list-callers-and-functions