table-plugin: row/column floating menu stays when a row/column is selected.

Selecting a row/column in table did throw a javascript exception regarding the selection range (rangy-core issue). This error is caught for IE7 and IE8, but not for document mode 7 or 8. Catching the error in case the document mode is less or equal than 8 solves the issue.
Merge pull request #1118 from najor/hotfix-rm12385-tabelle-selection

table-plugin: row/column floating menu stays when a row/column is selected