added .gitignore file to avoid committing build products and stray files

.gitignore

+*.o
+*.orig
+*.rej
+*diff
+TAGS
+autom4te.cache
+Makefile
+Makefile.in
+GNUmakefile
+GNUmakefile.in
+aclocal.m4
+configure
+config.log
+config.status
+libtool
+m4/generated
+m4/config
+.deps
+.libs
+*.lo
+*.la
+*.pd_linux
+*.pd_darwin
+*.d_fat
+*.d_fat_o
+po/*.msg
+bin
+src/pd
+src/pd-watchdog
+src/pdreceive
+src/pdsend
+ASIOSDK2
+pd-0.*
+pd.pc