-Add a parameter to R_ClipLine that specifies the minimum distance from the viewer for clipping. 
-R_AddLine clips anything closer than NEARCLIP while R_CheckBBox clips at 0.

git-svn-id: http://odamex.net/svn/root/branches/persdiv@3682 b0bcef46-2027-0410-bd56-ab726e9a1d04
-Add a check to determine if a masked seg is entirely above or below the viewing screen in R_RenderMaskedSeg. Remove the check in R_BlastMaskedColumn. This should be a more efficent way of preventing overflows when really close to offscreen masked segs.

git-svn-id: http://odamex.net/svn/root/branches/persdiv@3683 b0bcef46-2027-0410-bd56-ab726e9a1d04
-Add masktop and maskbottom arrays to keep track of the projected screen coordinates of the top and bottom of masked midtextures.
-Use masktop and maskbottom to determine if a masked midtexture column is visible (improved approach over r3683).
-Add macro FIXED2INT to convert fixed_t values to ints using rounding instead of truncation.
-Move FIXED2FLOAT, FLOAT2FIXED macros to m_fixed.h
-A bit of r_segs.cpp cleanup

git-svn-id: http://odamex.net/svn/root/branches/persdiv@3684 b0bcef46-2027-0410-bd56-ab726e9a1d04
-Fix an off-by-one error in the alignment of textures horizontally.

git-svn-id: http://odamex.net/svn/root/branches/persdiv@3685 b0bcef46-2027-0410-bd56-ab726e9a1d04
-Partial revert of r3684.

git-svn-id: http://odamex.net/svn/root/branches/persdiv@3686 b0bcef46-2027-0410-bd56-ab726e9a1d04
-Fix a couple bugs calculating stepping values.

git-svn-id: http://odamex.net/svn/root/branches/persdiv@3687 b0bcef46-2027-0410-bd56-ab726e9a1d04
-Add a version of R_PointInSubsector for the physics code (P_PointInSubsector) for compatibility purposes.
-Fixes issues walking across bridge-things on zdctf map04.

git-svn-id: http://odamex.net/svn/root/branches/persdiv@3688 b0bcef46-2027-0410-bd56-ab726e9a1d04
-Revert the rest of the masked midtexture clipping code from r3684.

git-svn-id: http://odamex.net/svn/root/branches/persdiv@3689 b0bcef46-2027-0410-bd56-ab726e9a1d04