Bump version number to 2.7.2

Bump version number to 2.7.1

Bump version number to 2.7

Added release script

Re-release of 2.5.4 as 2.5.5 without docs

Release 2.5.4 as well

fixed an operator precedence error introduced in 2.5.2.

Statements like "-foo.bar" had their implicit parentheses applied around
the first part of the expression ("(-foo).bar") instead of the more
correct "-(foo.bar)".

fixed an issue with unary operators having the wrong precendence.

--HG--
branch : trunk

Removed tag 2.5

--HG--
branch : trunk

fixed an error reporting bug for undefineds.

--HG--
branch : trunk