Remove unused main/desc_id.h
Move reactor Gun_dir,Gun_pos into struct object
Remove N_controlcen_guns cache

Get the counter directly from the relevant reactor model
Add stubs to hide editor reactor differences from D1X
Always use int[] for matcen robot flags
Fix bogus optimization in robot maker paging

The optimization meant to skip materialization centers which had no
robots enabled, but had two bugs.  It tested for a NULL address instead
of inspecting the bits in robot_flags[0], which caused the test to
always succeed.  It also ignored robot_flags[1], so a materialization
center with only high end robots would be wrongly skipped.

Remove the test, since the loop is cheap and handles all cases
correctly.
Rename old_matcen_info to reflect that it is the D1 matcen_info
Remove unused StartNewLevel parameter 'secret_flag'
Remove unused main/gamestat.h
Remove unused main/link.bat
Delete definition of Segment2s

This should have been part of 644f7ce9 ("Move segment2 back to
segment").
Move declaration of last_palette_loaded to gamepal.h
Avoid crash on failure to open HAM file
Remove unused declarations in main/screens.h
Remove unused gauge declarations
Remove unused hostage dialog editor
Make stub g3_uninit_polygon_model inline
Read robot_info arrays in pieces
Reorder differences to match D1X
Avoid using #ifdef inside Error string on hog failure