allow <== and >== as alternative for <= and >= in scripts
turned redeclartion of local variables from an error into a warning
Fix a case folding bug
Revert "Merge remote-tracking branch 'glorf/acrobatics'"

This reverts commit 089ef7a2a02d62c1bdaf3fa0fda470189f5182bb, reversing
changes made to 67422c397c883017b4ff6a7adfb405cdf767f807.
Merge remote-tracking branch 'scrawl/master'
Fixes Bug #734 'Book empty line problem'
Hides buttons 'Next' and 'Prev' at the last and at the first page