Report error if messages sent to plm are of an incorrect length

- Add sub insteon_cmd_len to Message_Decoder. Returns expected byte length
- Add error message if command sent to plm is improper length

* After testing need to add coding to skip sending an incorrect message

Start of fix for Hollie/misterhouse#83
Clear messages sent to PLM if of incorrect length
Remove no_hop_increase flag from NACK logic

Messages that are NACKed are dropped not resent.  So there is no concern that a hop_increase will be recorded.
POD added to ~_Items.pm
faq.pod update by Vargester requested by Stovenour
Enable DTR on the serial port when checking for new data from an MR26, as a CM17 on the same port may switch it off
Add a comment explaining why the DTR signal may need to be activated again
Merge pull request #106 from c99koder/MR26_FIX

Enable DTR on the serial port when checking for new data from an MR26
Merge pull request #105 from drobinson0919/master

POD added to ~_Items.pm
POD added to a dozen lib/~items.pm and doc/download.pod and html
Merge pull request #100 from krkeegan/fix_issue_83

Drop Bad Messages Sent to PLM
Merge pull request #101 from krkeegan/hop_tracking

Remove no_hop_increase flag from NACK logic
Fix Issue #104:  Add Objects, Items, and Modules links to TOC
Fix Issue #112:  Update installation instructions

Rewrote quick install instructions for both Windows and Unix
Rewrote windows detailed install instructions steps 1 and 2
Modified many of the links to be consistent and use POD L<> syntax
Replaced references to misterhouse, Misterhouse, Mister House, MH, and mh with MisterHouse
Ran spell check and corrected many typos
Fix Issue #113: Fix die issue when updating docs

Original code would create fake .pm entries in %libfiles while checking if .pm or .pl file exists.  This combined with a "or Die()" line in the next section of code caused the update to abort after processing one new .pl file.  Subsequent calls would again process one .pl file until eventually (if called every day) finishing all the .pl files. Also fixed ambiguous use of --htmldir and --htmlroot; man page says only one should be specified.
Merge pull request #114 from mstovenour/fix_issue_112

Fix Issue #112:  Update installation instructions
Merge pull request #115 from mstovenour/fix_issue_113

Fix Issue #113: Fix die issue when updating docs
Merge pull request #107 from drobinson0919/master

Documentation Updates
Fix Issue #116:  wiki stuck in frame from toc.html

Corrected issue and made minor formatting change to Developer section
Merge pull request #117 from mstovenour/fix_issue_116

Fix Issue #116:  wiki stuck in frame from toc.html