-remove "SIMD" option from "compile_wasm.py" (new Emscripten hasn't that option)

-removed some unnecessary variables
-started C-API implemantation:
 * added C-API option to Meson (build included to main library)
 * refactored some code (moved some code form templates to final code, removed delegates from system)
 * moved templates outside EntityManager to make it possible to use in different functions

c-api/meson.build

@@ -0,0 +1,7 @@
+src += files(
+	'manager.d'
+)
+
+c_src = files(
+	'test.c'
+)