Node tree builder does not use uppercase values for 'permission', but does not throw

[tswilliams]

If uppercase values are used for the permission attribute in the address table, then the node tree builder ignores these values and leaves the permission as READWRITE, but does not throw an exception. The same thing happens for completely invalid values.

Example address tables illustrating this bug:

<node fwinfo="endpoint;width=11">
  <node id="stat" address="0x0" permission="W" >
    <node id="mmcm_locked" mask="0x1"/>
    <node id="ready" mask="0x2"/>
  </node>
</node>

<node fwinfo="endpoint;width=11">
  <node id="stat" address="0x0" permission="bob" >
    <node id="mmcm_locked" mask="0x1"/>
    <node id="ready" mask="0x2"/>
  </node>
</node>

The node tree builder should be updated so that if the permissions attribute contains any invalid/unused characters, an exception is thrown.

[tswilliams]

In fixing this issue, I realised that exceptions were also not being thrown for some invalid values of the id, mode, address, mask and size attributes. These additional omissions have been resolved along with the original subject of this ticket (invalid values for the permission attribute) in pull request #171.