Fix warnings in generated lex.yy.c file

Also note them in the README.txt for future reference.

Change-Id: I3a99670a2717369e7d91df5a2c3ce5f0c7dd9c40
Remove unused variables in vtkWrapPythonInit

Change-Id: I2ebe22d4d9081e7635cfb22123cdc6f9d7887b6e
Merge topic 'unified-bindings-warning-sweep' into master

c760a265 Remove unused variables in vtkWrapPythonInit
9f3f7cef Fix warnings in generated lex.yy.c file