Enable compiler warnings
Add -Wno-format
Always enable IPv6
Simplify config.inc and use new reference BSP

Use arm/realview_pbx_a9_qemu as the new reference BSP.  This BSP offeres
NULL pointer read/write protection and runs on the Qemu simulator.  With
this BSP it is possible to run network tests which use a virtual network
based on TAP devices.
Use integer-only printf in kernel space
Use integer-only printf for ftpd
Use floating-point tasks for tests
Fix task create argument