Found a bug in prefer avoid filter.
   - added the MakeConsList to the filter list.
   - modified a bit TermCons.toString to better emphasize lists.
add --debug parameter to ktest and print stack traces only when that's used
add a line of documentation
replace some strings with constants for uniformity
check for --debug parameter when CLI parsing failed
fix windows backslash escaping
addressed issues in code reviews
Merge pull request #515 from yilongli/refactoring-hashCode

Refactoring hash code
KTEST: add it to manual how to skip steps
make BuiltinMap immutable; use builder pattern to avoid double-defensive copying both at Transformer and constructors
Merge pull request #522 from osa1/more-ktest-issues

fix exception reporting in ktest
Merge pull request #521 from osa1/ktest-issues

fix for #518
addressed issues in code review
update to latest version of jansi
I'm not sure which way to generate lists is better, so I'm reading the old code on a dead branch so I can test easier.
pretty printer: avoid to print the ListTerminator at the end of a syntatic list
replaced *.out files with generated outputs
modified the pretty printer to sort the cells of a bag according to the their order in user-declared configuration
updated *.out files in 4_imp++/lesson_6
updated *.out files in imp++/lesson_7