Add exact bounds support to ind_lim_vrange_dialog

[michaellans]

Added support for specifying exact bounds in the ind_lim_vrange_dialog. This is done by adding logic for a fourth option option_idx == 3 to the bounds options dictionary, and adding that option to the bounds scaling/calculation logic. This allows setting relative/exact bounds independently for each variable, rather than a global relative_to_current setting

• Added a new "exact_bounds" option to variable range selection dialog, with spinboxes for typing in bounds

• Updated the bounds scaling calculation and auto-bounds logic to handle "exact_bounds". I also added this to the main GUI routine_page, as the ind_lim_vrange_dialog is shared

• Also updated the dialog to display current bounds below the current value.

• Tested setting/saving exact_bounds with templates, this worked well without needing further changes

• Simplified tooltips for when bounds are clipped.