Wasm port

[alpha0010]

Opening this for discussion. It is functional, but makes some fundamental changes that need to be considered before merging.

Demo: https://alpha0010.github.io/terramap/

I attempted to port the file reader and map renderer to C++ Wasm (used some code from my Terra AWG project).

To compile, execute emmake make -j8 (requires emscripten installed) in the wasm/src folder. (There is also a cli test utility you can build via make -j8 cli.)

Pros:

• About 4x faster than the batch render optimization that is already live
• Able to read some older files the JS implementation fails on
• Displays wires and paint on the map
• Block highlight worst case (e.g. select all stone blocks) is massively faster (and does not freeze the UI while running)
• More details in world info and tile properties menus
• Fixes colors for some blocks that were just displaying as black

Cons:

• Requires a compile step (GitHub pages deployment is still possible, but needs a custom workflow set up, not just regular branch deployment)
• Requires understanding of C++
• Much more complicated logic for passing messages between execution layers
• Uncertain how this functions on other browsers/operating systems, since while Wasm is not a new technology, it is much newer than plain JS
• Display render is no longer incremental (but this runs fast enough that maybe that is okay?)

I know the hardest part of an open source project is the long term maintenance, so feel no obligation to take this pull request. I mainly did it as a study case to experiment with Wasm technologies.