Allows the user to configure a file for their Phidgets Interface Kit.
mappings.txt contains the key-value pairs as such:
  alias:port

Then users can read the current value via a defined alias.

Example:
  I define the following configuration
    light:1
    temperature:3
  Provided the configuration matches my Interface Kit I can then call out to
  the individual Phidgets.
  ./readphidget light
  -returns current light sensor value
  ./readphidget temperature
  -returns current temperature sensor value

To cross compile:
  SYSROOT=(..)/OpenWrt-SDK-brcm47xx-for-Linux-i686-gcc-4.3.3+cs_uClibc-0.9.30.1/staging_dir/toolchain-mipsel_gcc-4.3.3+cs_uClibc-0.9.30.1/
  PATH=$SYSROOT/usr/bin:$PATH
  export CXX="mipsel-openwrt-linux-g++ --sysroot $SYSROOT"
  export LDFLAGS="-L$SYSROOT/../target-mipsel_uClibc-0.9.30.1/usr/lib"
  export CXXFLAGS="-I$SYSROOT/../target-mipsel_uClibc-0.9.30.1/usr/include"