Add a *ton* of const and constexpr around the codebase. (#1864)

* Add a *ton* of const and constexpr around the codebase.

This makes the codebase compile without strings being cast to non-const char*. I also went through and added constexpr where appropriate for tons of static data.

* Make process definitions const too

Might as well

src/d/d_envse.cpp

@@ -248,7 +248,7 @@ static leafdraw_method_class l_dEnvSe_Method = {
     (process_method_func)dEnvSe_Draw,
 };
 
-kankyo_process_profile_definition g_profile_ENVSE = {
+DUSK_PROFILE kankyo_process_profile_definition DUSK_CONST g_profile_ENVSE = {
     /* Layer ID      */ fpcLy_CURRENT_e,
     /* List ID       */ 2,
     /* List Prio     */ fpcPi_CURRENT_e,