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/calc_distort.cc

@@ -84,7 +84,7 @@ int calcDistortion(unsigned char* img1, unsigned char* img2, int ncols, int nrow
 
             r0[n] = sqrt((x0 - wc) * (x0 - wc) + (y0 - hc) * (y0 - hc)) / radius;
 
-            // dots too close to the center tends to have big diviation and create noise, extract them
+            // dots too close to the center tends to have big deviation and create noise, extract them
             if (r0[n] < CENTER_R) {
                 continue;
             }