Rename all functions to use the names corresponding to their NIDs - #169

For renaming syscalls, I was thinking we should either

1. Rename them to snake case (this is how the official SDK does it according to the known NID names and usage of them in projects like LuaJIT)
2. Keep them as is
3. Keep the current casing, but prefix with cellKernel to match the PSP/PSVita/PS4 where syscalls use the sceKernel prefix

I am fine with doing this in another PR tho

Also should I make it so it's cellRsx instead of rsx for librsx?

@zeldin any feedback or comments about this change? your input will be useful as you have all the experience and background from PSL1GHT since early days

First of all, there's a lot of unrelated changes in this PR. I started calling them out, but it was just so massive sloppiness so I got tired of it. This change set is large enough as it is without a lot of irrelevant stuff tacked on.

Secondly, just adding "cell" at the beginning of every name seems pretty gratuitous to me, but I suppose this is done to make the names match the hashes? If this is done it becomes necessary to provide aliases with the old names, or else you will break every program using the old names...

The changes to Makefiles were so I could compile all samples to make sure they still worked, I can undo the makefile changes and doxygen/.gitignore, those were accidental, apologies.

I do plan on adding aliases to the old names, that's why it is marked as a draft.

The channges ares mostly to match the naming scheme of the official hashes yes. Similar to how PSP/PSVita use the sce prefix in their Homebrew SDKs, I felt for new users who were used to PSPSDK and VitaSDK, doing this change would make sense.

@zeldin I tried fixing the sloppyness, hope this is better now, apologies. Now it's just renames, removes exactly as much as it adds.
If it is even desired to make the funcs match the hashes, I will work on adding the compatiblitity defines, which by the way, should they be gated behind a define, or no?