Fix various typos

Found via `codespell -q 3 -S ./rtdata/languages -L activ,alph,ba,bloc,bord,chang,childs,currentry,dof,dum,fo,hist,inout,invers,lonly,makro,ois,pres,preserv,portugues,rady,reall,redy,struc,tbe,thre,trough,vart,vekto`

rtengine/cJSON.c

@@ -126,7 +126,7 @@ typedef struct internal_hooks
 } internal_hooks;
 
 #if defined(_MSC_VER)
-/* work around MSVC error C2322: '...' address of dillimport '...' is not static */
+/* work around MSVC error C2322: '...' address of dllimport '...' is not static */
 static void *internal_malloc(size_t size)
 {
     return malloc(size);