add Croatian language and dictionary

Dictionary with frequencies taken from OpenBoard and cleaned up from
non-Croatian words.

Rest of the words without frequency taken from Rječnik hrvatskih jezika
(https://github.com/gigaly/rjecnik-hrvatskih-jezika).

app/languages/definitions/Croatian.yml

@@ -0,0 +1,13 @@
+locale: hr
+dictionaryFile: hr-utf8.csv
+layout:
+  - [SPECIAL] # 0
+  - [PUNCTUATION] # 1
+  - [a, b, c, č, ć] # 2
+  - [d, e, f, đ] # 3
+  - [g, h, i] # 4
+  - [j, k, l] # 5
+  - [m, n, o] # 6
+  - [p, q, r, s, š] # 7
+  - [t, u, v] # 8
+  - [w, x, y, z, ž] # 9