Bug #1738: expr_bool.y differentiates between value 0 and element not found
Bug #1738: expr_bool.y returns -1 if the type does not match
Bug #1738: Cleanup code using xpath | operator
Bug #1738: Compile parsers
Feature #1747: Allow xpath in rank and requirements expressions
Feature #1747: Compile commit:73687ce
Word wrap options description in CLI help
bug #1738: Complie with latests flex and yacc
Merge branch 'bug-1738'