Node size attribute silently ignored without mode attribute

[tswilliams]

In an address table, if the size attribute is specified without a mode attribute, the value of the size attribute is not used (the node is interpreted as a single-word node of size 1), and uHAL does not throw an exception or issue any warning.

For example:

<node>
  <node id='regA' address='0x0' />
  <node id='regB' address='0x1' size='blah'/>
  <node id='ram1' address='0x100' mode='block' size='256' />
  <node id='ram2' address='0x210' mode='block' size='16' />
  <node id='aPort' address='0x300' mode='port' size='1024' />
</node>

(Here, the offending node is regB.)

Really, uHAL should throw an exception if any node has a size attribute but no mode attribute, since the attribute's value is unused and silently ignoring it may confuse users. However, to give people time to correct any address tables for a few releases, the code should first be updated to just issue a warning message that states that offending address tables should be fixed.