migrated index manipulation functions to a new file

src/gamedata/indices.rs

@@ -0,0 +1,26 @@
+pub fn inc_row((row, col): &(usize, usize), value: usize) -> (usize, usize) {
+    (row + value as usize, *col)
+}
+pub fn inc_col((row, col): &(usize, usize), value: usize) -> (usize, usize) {
+    (*row, col + value as usize)
+}
+
+pub fn dec_row((row, col): &(usize, usize), value: usize) -> (usize, usize) {
+    (row - value as usize, *col)
+}
+pub fn dec_col((row, col): &(usize, usize), value: usize) -> (usize, usize) {
+    (*row, col - value as usize)
+}
+pub fn inc_both((row, col): &(usize, usize), value: usize) -> (usize, usize) {
+    (row + value, col + value)
+}
+pub fn dec_both((row, col): &(usize, usize), value: usize) -> (usize, usize) {
+    (row - value, col - value)
+}
+//TODO get better names for these
+pub fn inc_dec((row, col): &(usize, usize), value: usize) -> (usize, usize) {
+    (row + value, col - value)
+}
+pub fn dec_inc((row, col): &(usize, usize), value: usize) -> (usize, usize) {
+    (row - value, col + value)
+}