pcbnew: change options of interactive routing on the fly

[Eldar Khayrullin]

Change options of interactive routing on the fly doesn't work or artefacts appear when changing modes (e.g. from Shove to Highlight mode).

Application: kicad
Version: 4.1.0-alpha+201606281446+6952~45~ubuntu16.04.1-product, release build
Libraries: wxWidgets 3.0.2
           libcurl/7.47.0 OpenSSL/1.0.2g zlib/1.2.8 libidn/1.32 librtmp/2.3
Platform: Linux 4.4.0-24-generic x86_64, 64 bit, Little endian, wxGTK
- Build Info -
wxWidgets: 3.0.2 (wchar_t,wx containers,compatible with 2.8)
Boost: 1.58.0
Curl: 7.47.0
KiCad - Compiler: GCC 5.3.1 with C++ ABI 1009
        Settings: USE_WX_GRAPHICS_CONTEXT=OFF
                  USE_WX_OVERLAY=OFF
                  KICAD_SCRIPTING=ON
                  KICAD_SCRIPTING_MODULES=ON
                  KICAD_SCRIPTING_WXPYTHON=ON
                  USE_FP_LIB_TABLE=HARD_CODED_ON
                  BUILD_GITHUB_PLUGIN=ON