organization in the src structure, modification of README

src/builtin_structures/numbers/convert_from_decimal.py

@@ -0,0 +1,24 @@
+#!/usr/bin/python3
+# mari von steinkirch @2013
+# steinkirch at gmail
+
+def convert_from_decimal(number, base):
+    ''' convert any decimal number to another base. '''
+    multiplier, result = 1, 0
+    while number > 0:
+        result += number%base*multiplier
+        multiplier *= 10
+        number = number//base
+    return result
+
+
+def test_convert_from_decimal():
+    number, base = 9, 2
+    assert(convert_from_decimal(number, base) == 1001)
+    print('Tests passed!')
+
+
+if __name__ == '__main__':
+    test_convert_from_decimal()
+
+