Differences between 2.0 and 2.1 in term of Modding.

There's not many pages that cover this in the internet (I couldn't find one), What are the differences (besides LUA Support) in term of Modding between 2.0.X and 2.1.X, What features have been deprecated and what are their alternatives, This would make things alot easier if anyone intends to Port some 2.0.X Mods to 2.1.X.

I know for a fact, character wads were handled differently with 2.1 than compared to 2.0 with different frames. For example, if you add a 2.0 character into 2.1, their Life Monitor icon will be messed up because back in 2.0, you needed to sprite your own monitor with your characters face on it. Same with the End Sign. In 2.1, all you have to do is add your character's face/pose to the End Sign but in 2.0, you had to sprite the sign yourself as well as put your character in it. If you added a 2.0 character to 2.1 now, the Life Monitor will have another monitor "inside" the life monitor and the End Sign will have the sprited monitor of your character inside the sign.

Here's some things I can remember off the top of my head:

* 2.0 used the TEXTURE1/TEXTURE2 and PNAMES lumps to define all textures. In 2.1 none of these lumps are needed; most single-patch textures can just be Doom graphic lumps between TX_START/TX_END, while all multi-patch textures (and sometimes single patch textures) are defined by the TEXTURES lump.

* This isn't a "deprecated feature" thing but 2.1 also supports tall patches unlike 2.0, which means patches/sprites can be taller than 255 pixels. This alone means we can make all skies and other large textures a single patch each, for instance.

* 2.0's barebones "SRB1 mode" typeoflevel (which just changed thok speed and jump height?) was merged with 2D mode.

* In 2.0, linedef types 405, 406, 407 and 408 all used to be linedef exec types for moving planes by linedef distances. In 2.1 we made them based on texture offsets instead, and 406/408 were removed for being redundant.

* I vaguely remember Enable/Disable 2D Mode (linedef type 432) originally being two separate linedef types in 2.0?