adding fb1-5 flex&bison example

fixing after gcc warning/suggestion

adding nounput & noinput options to the lex files

allowing to add own CFLAGS & setting default cflags

allowing to set the --header-file= option by setting variable

adding rule for bison files

using $^ for all prerequisites

using LEX instead of FLEX

adding fb1-4.l

adding comment to make code more readable

simplifying the make rules

adding fb1-3.l

fixing capitalization in header in readme

adding -rf to the clean target

adding fb1-2.l