Evas filters: Improve doc automatization

Include example filter codes from src/examples in Doxygen.
Use these examples for the generation as well.

evas/filters/filter_blend.txt

@@ -0,0 +1 @@
+blend (color = #3399FF);

evas/filters/filter_blur.txt

@@ -0,0 +1,2 @@
+blur (10, color = black, oy = 5, ox = 5);
+blend ();

evas/filters/filter_bump.txt

@@ -0,0 +1,3 @@
+buffer : a (alpha);
+blur (5, dst = a);
+bump (map = a, compensate = yes, color = cyan, specular = 10.0);

evas/filters/filter_curve.txt

@@ -0,0 +1,4 @@
+buffer : a (alpha);
+blur (4, dst = a);
+curve (0:0 - 20:0 - 60:255 - 160:255 - 200:0 - 255:0, src = a, dst = a);
+blend(src = a, color = black);

evas/filters/filter_example_1.txt

@@ -0,0 +1,5 @@
+buffer : fat (alpha);
+grow (8, dst = fat);
+blur (12, src = fat, color = darkblue);
+blur (4, color = cyan);
+blend ();

evas/filters/filter_grow.txt

@@ -0,0 +1,4 @@
+buffer : fat (alpha);
+grow (4, dst = fat);
+blend (src = fat, color = black);
+blend (color = white);

evas/filters/filter_mask.txt

@@ -0,0 +1,5 @@
+buffer: a (alpha);
+blur(5, dst = a);
+curve(points = 0:255 - 128:255 - 255:0, src = a, dst = a);
+blend(color = black);
+mask(mask = a, color = cyan);

evas/filters/filter_transform.txt

@@ -0,0 +1,4 @@
+buffer : t (alpha);
+transform (oy = 20, dst = t);
+blend (src = t, color = silver);
+blend (color = white);