added support for menu list entry size for game elements info screen

This commit adds support for using the following three graphics
configuration options to customize the available size (height),
spacing between lines of text and spacing between list entries
for the list of game element graphics and descriptions on the
game elements info screen:

* menu.list_entry_size.INFO[ELEMENTS] - available height for text
* menu.line_spacing.INFO[ELEMENTS]    - space between lines of text
* menu.extra_spacing.INFO[ELEMENTS]   - space between list entries