Feature Request: Assign to close icon the same color of the main icon

**jquery-confirm version:**
v3.x.x

**I'm submitting a ...**  (check one with "x")
[ ] bug report
[X] feature request
[ ] support request

**Current behavior:**
You can set 'type' to 'red' or 'blue', or any other color and close icon remains black.

**Expected behavior:**
I think that colour of close icon have to be the same as main icon, according to the 'type' option.
