Add Build System documentation to the library manual. Update CPPCHECK build system module so that it uses the SRC variable rather than just the project directory.

LUFA/DoxygenPages/CompilingApps.txt

@@ -45,4 +45,6 @@
  *  diagnostic output files), execute <b>"make clean"</b>. Once a "make all" has been run and no errors were encountered, the
  *  resulting binary will be located in the generated ".HEX" file. If your project makes use of pre-initialized EEPROM
  *  variables, the generated ".EEP" file will contain the project's EEPROM data.
+ *
+ *  \see \ref Page_BuildSystem for information on the LUFA build system.
  */

LUFA/DoxygenPages/ConfiguringApps.txt

@@ -21,6 +21,8 @@
  *
  *  Below is a copy of the default LUFA application makefile, which can be used as a template for each application.
  *
+ *  \see \ref Page_BuildSystem for information on the LUFA build system.
+ *
  *  \verbinclude makefile_template
  *
  *  Inside each makefile, a number of configuration variables are listed with the syntax "<VARIABLE NAME> = <VALUE>". For

LUFA/DoxygenPages/DevelopingWithLUFA.txt

@@ -11,6 +11,7 @@
  *  information on compile-time tuning of the library and other developer-related sections.
  *
  *  <b>Subsections:</b>
+ *  \li \subpage Page_BuildSystem - The LUFA Buildsystem
  *  \li \subpage Page_TokenSummary - Summary of Compile Time Tokens
  *  \li \subpage Page_Migration - Migrating from an Older LUFA Version
  *  \li \subpage Page_VIDPID - Allocated USB VID and PID Values