[ck2cti] Fix support for species names containing '+' and '='

This addesses a parsing error that would occur if a mechanism contained both
'foo' and 'foo+', where reactions written as 'foo+bar' would be parsed as a
reaction with 'foo+' and 'bar'.

See Issue 182.

Cherry pick of trunk commit r2701.

git-svn-id: https://cantera.googlecode.com/svn/cantera/branches/2.1@2714 02a645c2-efd0-11dd-984d-ab748d24aa7e