Support for ORTHO_VIEWS has been broken since commit
db514a5ded in December 2004.
`git blame HEAD -L872,+4 -- similar/editor/meddraw.cpp`:
```
db514a5ded main/editor/meddraw.c (Bradley Bell 2004-12-19 13:54:27 +0000 872) }
db514a5ded main/editor/meddraw.c (Bradley Bell 2004-12-19 13:54:27 +0000 873) } else
db514a5ded main/editor/meddraw.c (Bradley Bell 2004-12-19 13:54:27 +0000 874) #if ORTHO_VIEWS
db514a5ded main/editor/meddraw.c (Bradley Bell 2004-12-19 13:54:27 +0000 875) else if ( screen_canvas == TopViewBox->canvas )
```
When ORTHO_VIEWS is true, this code expands to `} else else if (...)`; a
double-else is not legal, so the code cannot have been compiled with
ORTHO_VIEWS enabled. All 4 of the relevant lines date to db514a5ded,
which itself is an import of files from the D1X editor.
Previously, valptridx used PREFIX for allow-invalid+mutable, c#PREFIX
for allow-invalid+const, v#PREFIX for require-valid+mutable, vc#PREFIX
for require-valid+const. Convert the types, factories, and all usage
sites to specify a qualifier for all four combinations:
im#PREFIX -> allow-invalid+mutable
ic#PREFIX -> allow-invalid+const
vm#PREFIX -> require-valid+mutable
vc#PREFIX -> require-valid+const
Changes to common/include/valptridx.h and common/include/fwd-valptridx.h
are manual. All other changes are generated by:
git grep -lz -e '\(obj\|seg\|clwall\|wall\|actdoor\|trg\)\(ptridx\|ptr\|idx\)\(_t\)\?\>' | xargs -0 sed -i -e 's/\<\(v\?\)\(\(obj\|seg\|clwall\|wall\|actdoor\|trg\)\(ptridx\|ptr\|idx\)\(_t\)\?\)\>/\1m\2/g'
for the 'm' prefix and:
git grep -lz -e '\(obj\|seg\|clwall\|wall\|actdoor\|trg\)\(ptridx\|ptr\|idx\)\(_t\)\?\>' | xargs -0 sed -i -e 's/\<\([cm]\(obj\|seg\|clwall\|wall\|actdoor\|trg\)\(ptridx\|ptr\|idx\)\(_t\)\?\)\>/i&/g'
for the 'i' prefix.