Pjsua as registration fuzzer

Pjsua version intended to work as SIP fuzzer for registration. Modified from pjproject-2.4. Built with VS2013 with Platform Toolset set for Release target to Windows XP / v120_xp (that is compatible with Windows XP and above, by default binaries produced with VS2013 are not compatible with WinXP).

Building from source seems to require separate DirectX SDK download. After switching to v120_xp toolset VS2013 (Community Edition) doesn't link with DX libraries from included Windows Kits 8.0 and 8.1. Other problem is error in IPHlpApi.h header from Windows SDK 7.1A: #if (NTDDI_VERSION >= NTDDI_XP) should be replaced with #if (NTDDI_VERSION >= NTDDI_WINXP).

Changes from "regular" pjsua:

Downloads:

Command line builder

Creating command line with multiple account configurations.

Options:

Registrar
Starting username (numeric!)
Password (same for every account)
Use username as password
Number of accounts to create

Command:

Note: maximum length of command line handled by Windows is limited, e.g. limit in Windows XP allows passing configuration of about 50 accounts. Larger numbers of accounts have to be split between multiple pjsua instances.