Implement new configuration option "DefaultUserModes"

The new configuration option "DefaultUserModes" lists user modes that
become automatically set on new local clients right after login.

Please note that only modes can be set that the client could set on
itself, you can't set "a" (away) or "o" (IRC Op), for example! User
modes "i" (invisible) or "x" (cloaked) etc. are "interesting", though.

Default: set no modes (like without this patch).

Closes bug #160.
Save client IP address text for "WebIRC" users

This patch introduces a new field in the CLIENT structure, "ipa_text",
which points to an optional textual representation of the client IP
address (or NULL) which can be used to store the "real" IP address
information of a client using the "WEBIRC" protocol.

Without this patch, ngIRCd ignored the <ip-address> paramater ...

In addition, the functions Client_SetIPAText() and Client_IPAText()
have been introduced to set and get the textual representation of the
client IP address.

Client_IPAText() can be used even when no "IP address text" has been
set before, it then returns the real IP address of the connection.

Closes bug #159.
Introduce Free_Client() function to free CLIENT structure
Merge branch 'bug159-WebircIPA'

* bug159-WebircIPA:
  Introduce Free_Client() function to free CLIENT structure
  Save client IP address text for "WebIRC" users
Xcode: update project settings for Xcode 5