add a cool lua repl

lib/lua-term/core.c

@@ -0,0 +1,27 @@
+#define _POSIX_C_SOURCE 200112L
+
+#include <lua.h>
+#include <lauxlib.h>
+#include <lualib.h>
+#ifndef _MSC_VER
+# include <unistd.h>
+#endif
+
+static int
+lua_isatty(lua_State *L)
+{
+    FILE **fp = (FILE **) luaL_checkudata(L, 1, LUA_FILEHANDLE);
+
+    lua_pushboolean(L, isatty(fileno(*fp)));
+    return 1;
+}
+
+int
+luaopen_term_core(lua_State *L)
+{
+    lua_newtable(L);
+    lua_pushcfunction(L, lua_isatty);
+    lua_setfield(L, -2, "isatty");
+
+    return 1;
+}