examples: use filenames from argv instead of hardcoded strings

examples/modifySymbolValue.py: modify "strlen" entry instead of
"printf" entry (example script should work with more binaries now)
examples/addRandomSections.py: add option for deterministic results (...)

also:
- use filenames from argv instead of hardcoded strings
- reduce number of random sections from 10000 to 128 (to speed up
  large number of automated tests)
examples/indirectJmpWithMemoryData.py: remove loops where possible

(old and new version produce same result for selected set of >900
binaries)
add .gitignore (and ignore *.pyc)