fixed compilation with libxl 2.5.4
Added Sheet::setRightToLeft() and Sheet::setRightToLeft() methods that specifies whether the sheet in is "right to left" display mode
Added Book::isTemplate() and Book::setTemplate() methods for detecting xltx files and converting from xlsx to xltx and vice versa
make _php_excel_date_unpack return long instead of int. This fixes a bug with dates > 2038
added testcase for dateunpack_overflow bug
Merge pull request #59 from ederuiter/master

Fix for overflow in _php_excel_date_unpack due to int return type instead of long
change to long
 fixed typo
Added excel.skip_empty INI setting that allows null values to be skipped, if set to 2 the empty strings will be skipped as well
update license
Merge branch 'master' of https://github.com/iliaal/php_excel