dcrlncli - code review

[fguisso]

With this PR on dcrdocs to include dcrlncli commands, we found various typo error and lack of explain. Then I decided to create a to-do list for code review each command to fix it and enjoy the time to analyze the code and make some improvements.

• [x] openchannel
• [x] closechannel
• [x] closeallchannels
• [x] abandonchannel
• [x] channelbalance
• [x] pendingchannels
• [x] listchannels
• [x] closedchannels
• [x] getchaninfo
• [x] getnetworkinfo
• [x] feereport
• [x] updatechanpolicy
• [x] exportchanbackup
• [x] verifychanbackup
• [x] restorechanbackup
• [x] estimatefee
• [x] sendmany
• [x] sendcoins
• [x] listunspent
• [x] listchaintxns
• [x] sendpayment
• [x] payinvoice
• [x] sendtoroute
• [x] addinvoice
• [x] lookupinvoice
• [x] listinvoices
• [x] listpayments
• [x] queryroutes
• [x] decodepayreq
• [x] fwdinghistory
• [x] cancelinvoice
• [x] addholdinvoice
• [x] settleinvoice
• [x] connect
• [x] disconnect
• [x] listpeers
• [x] describegraph
• [x] getnodeinfo
• [x] create
• [x] unlock
• [x] changepassword
• [x] newaddress
• [x] walletbalance
• [x] signmessage
• [x] verifymessage
• [x] wtclient

[fguisso]

dcrlncli newaddress in #86