doc: Use lowercase for 2D raster mask and other masks (#4495)

Similarly to #4401, this replaces usage of MASK by mask on additional places. It also improves wording of a warning in i.fft.

imagery/i.fft/main.c

@@ -105,8 +105,9 @@ int main(int argc, char *argv[])
     inputfd = Rast_open_old(Cellmap_orig, "");
 
     if (Rast_maskfd() >= 0)
-        G_warning(_("Raster MASK found, consider to remove "
-                    "(see man-page). Will continue..."));
+        G_warning(_("Raster mask active, consider removing it"
+                    " and running again without it (see documentation for"
+                    " details). This current process will now continue..."));
 
     G_get_set_window(&window); /* get the current window for later */
 

imagery/i.pca/i.pca.html

@@ -11,7 +11,7 @@ <h2>DESCRIPTION</h2>
 principal component with the highest importance.
 
 <p>
-The current geographic region definition and MASK settings are
+The current geographic region definition and raster mask settings are
 respected when reading the input raster map layers. When the rescale
 option is used, the output files are rescaled to fit the min,max range.
 

lib/ogsf/gk.c

@@ -172,8 +172,8 @@ void gk_follow_frames(Viewnode *view, int numsteps, Keylist *keys, int step,
 
         GS_get_from(tmp);
         G_debug(3, "gk_follow_frames():");
-        G_debug(3, "  MASK: %lx", mask);
-        G_debug(3, "  FROM: %f %f %f", tmp[X], tmp[Y], tmp[Z]);
+        G_debug(3, "  mask: %lx", mask);
+        G_debug(3, "  from: %f %f %f", tmp[X], tmp[Y], tmp[Z]);
 
         /* ACS 1 line: was      GS_get_focus(tmp);
            with this kanimator works also for flythrough navigation

lib/ogsf/gvd.c

@@ -201,7 +201,7 @@ int gvd_vect(geovect *gv, geosurf *gs, int do_fast)
                         }
                         gsd_endline();
                     }
-                    /* need to handle MASK! */
+                    /* need to handle mask! */
                     else if (src == CONST_ATT) {
                         /* for now - but later, do seg intersect maskedge */
                         if (gs_point_is_masked(gs, bgn) ||

raster/r.fill.dir/r.fill.dir.html

@@ -69,11 +69,11 @@ <h2>DESCRIPTION</h2>
 attributes required by other hydrological models.
 
 <p>
-As any GRASS GIS module, <em>r.fill.dir</em> is sensitive to the
-computational region settings. Thus
+As any GRASS GIS module, <em>r.fill.dir</em> respects the
+computational region settings. Thus,
 the module can be used to generate a flow direction map for any
-sub-area within the full map layer. Also, <em>r.fill.dir</em> is
-sensitive to any raster <em>MASK</em> in effect.
+sub-area within the full raster map layer. Also, <em>r.fill.dir</em>
+will take into account an active raster mask.
 
 <h2>NOTES</h2>
 

raster/r.li/TODO

@@ -24,12 +24,13 @@ d.vect forests type=boundary
 
 ######## TODO: CHECK THIS:
 
-# MASK test
-g.copy rast=fields,MASK
+# Test with raster mask
+r.mask raster=fields
 r.li.patchdensity forests conf=movwindow7 output=forests_p_dens7mask --o
 d.erase
 d.rast.leg forests_p_dens7mask
-# -> no negative values! but MASK is respected
+r.mask -r
+# -> no negative values! but mask is respected
 
 # zero data test
 r.mapcalc "forests = 0"

raster/r.univar/r.univar.html

@@ -53,7 +53,7 @@ <h3>PERFORMANCE</h3>
 <p>
 <em>r.univar</em> supports parallel processing using OpenMP. The user
 can specify the number of threads to be used with the <b>nprocs</b> parameter.
-However, parallelization is disabled when the MASK is set.
+However, parallelization is disabled when the raster mask is set.
 
 <p>
 Due to the differences in summation order, users may encounter small floating points