use dynamic texture mechanism

[shevernitskiy]

Will work with DFHack/dfhack#3663 only.

[myk002]

I think I prefer this API to what we had before. I'm not sure if it's perfect, but it's absolutely better. Just stylistic notes, but otherwise looks good.

could you use single quotes around the asset paths? we've mostly standardized on single quotes for strings in our Lua code.

[myk002]

wait -- after writing that suggestion of return texpos >= 0 and texpos or nil so many times, something struck me -- why don't we just have getAsset return nil if the texture isn't found/isn't valid? that would clean up the Lua usage patterns. If it's still useful for it to return -1 in cpp, then there can be a translation at the LuaApi.cpp layer.

[shevernitskiy]

wait -- after writing that suggestion of return texpos >= 0 and texpos or nil so many times, something struck me -- why don't we just have getAsset return nil if the texture isn't found/isn't valid? that would clean up the Lua usage patterns. If it's still useful for it to return -1 in cpp, then there can be a translation at the LuaApi.cpp layer.

That's right!
Cpp api should do all centralized work, lua should just use.
Maybe it can be the next iteration of rework textures? Refactor? There i will need some help:)
(if my cpp level is "look, it is compiles", but lua level is "what the heck, what is this? where are braces? where are types?!") :))

[shevernitskiy]

As I mentioned in main PR, it will be useful and more clear to move assets loading to lua plugin, where we can declare callbacks to get specific asset more centralized. Other plugins and scripts will just use this callbacks.
And all checks could move to cpp and/or to that asset init part.