Developer release v0.9.7

tenyr v0.9.7 is a development pre-release. Notable changes since v0.9.6 include :

• support for @symbol - .Llocal expressions
• updates to support bison 3.4.1 by replacing deprecated bison directives
• a nominal, arbitrary limit of 2048 bytes on symbol lengths in version 2 objects (to promote runtime memory safety)
• removal of memory leaks and misuse (e.g. read after free), mostly introduced by version 2 objects