Make mentions appear like in client

[MineRobber9000]

For example, this thread.

In bbjphp:

In bbj:

In bbjphp with fixed mentions (I used Inspect Element to fake the intended change):

[MineRobber9000]

Does str_replace take a function, like Python's re.sub?

EDIT: It's str_replace.

EDIT2: It doesn't, but there's a function that does.