Refactor network, paratime and account commands

[matevz]

Implements #73 .

Also:

• splits account.go into account/ folder containing file for each subcommand
• splits network.go into network/ folder containing file for each subcommand
• splits paratime.go into paratime/ folder containing file for each subcommand
• adds gas costs and debonding interval to network info
• adds selectors for network-only and network-account-only
• splits TransactionFlags to TxFlags and RuntimeTxFlags (e.g. only runtimes support --encrypted flag and may give false sense of security to the user for consensus transactions)
• fixes regression introduced in feat(cmd): Add support for outputting unsigned transactions #67 in contract command if --unsigned used
• adds shorthand aliases for root commands
• number of stylistic changes in the UI (paratime -> ParaTime, consistent === TITLES ===)

[kostko]

Initial comments, haven't reviewed everything yet.