Remove _Ptr(_Const) typedefs

[glebm]

Removes these typedefs because pointers should be handled with care. Having them visually stand out in the code helps us avoid common pitfalls, such as accidentally using Ptr instead of Obj.

This change has been automatically generated using the following command (GNU sed, for macOS and FreeBSD use sed -i ''):

find src \( -name '*.cpp' -o -name '*.hpp' \) -exec sed -i \
'/typedef.*_Ptr[_;]/d;'\
's/\([A-Za-z_]*\)_Ptr_Const/const \1*/g;'\
's/\([A-Za-z_]*\)_Ptr/\1*/g;'\
's/\([a-z]\)##\*/\1*/g' '{}' \+

Fixes #2785

[glebm]

@xzyfer Merging this won't cause any problems for @mgreter, as he can just apply the same sed command to his outstanding PR.