Lua from C.

• Initialize Lua (with a custom allocator).
• Set up the stack and call a Lua function with arguments from C.
• Provide a C procedure to be called from Lua.
• Print out the return value of the function.

$ make && ./main
clang main.c -Ilua-5.4.7/src lua-5.4.7/src/liblua.a -lm -o main
Adding:	25	24	20
Result of add is 69.