v 0.5.0

With the release of v0.5.0 there are a lot of changes in the current implementation
of the RegLog system. Most of the changes were implemented to provide more
customization options in implementing shiny.reglog in your ShinyApp and to
widen its possibilities. At the same time I've strived to make the historical
features still accessible, so it shouldn't be harder to use for novice
Shiny developers.

Instead of using single function to run all logic for RegLog system (as was the
case in deprecated login_server) it introduces three main components:
RegLogServer, two dbConnectors and two mailConnectors. Below are listed
the main changes and improvements over previous release. For more details
you can read two detailed vignettes: RegLogServer object: fields and methods
and Creating custom RegLogConnector handlers.

• main logic is now encapsulated in RegLogServer R6 class. Arguments provided during
  initialization of object provide options for customization, and more importantly
  objects of classes providing connection to the database (RegLogDBIConnector or
  RegLogGsheetConnector) and to your e-mail provider (RegLogEmayiliConnectororRegLogGmailrConnector`).
  • application can now observe for all state changes made during the lifespan
    of the application accessing the RegLogServer$message() reactiveVal.
  • default modalDialogs can now be inhibited - either all together (use_modals = F)
    or specifically (providing named list of FALSE bool values to use_modals argument)
  • is_logged, user_id, user_mail values are now kept inside reactiveVal
    fields, so you need to add () to access their values (eg. RegLogServer$user_id()).
    Also, account_id value is added for logged users.
• the improved presentation of password reset procedure don't make it necessary
  for invoking modalDialog. It makes the UI more flexible for this process more
  flexible.
• there is also added logic for credentials change procedure: it is now possible
  to change password, user ID and user e-mail after registration.
• class RegLogGsheetConnector provides support for storing the userbase inside
  googlesheet. It contains the past functionality of db_method = 'gsheet' in
  login_server.
  • there have been made some additional improvements: now it mirrors the behaviour
    of SQL databases: password changes don't append new rows to the googlesheet,
    but changes the whole row accordingly, which makes menaging the database
    much simpler.
• class RegLogDBIConnector provides support for storing the userbase inside
  DBI handled database. It improves on original support for SQLite database,
  providing also out-of-box support for multiple MySQL, MariaDB and PostgreSQL
  databases.
• both mailConnectors improves on the functionality of emailing methods
  of now deprecated login_server.
  • they allow explicitly modifying all send e-mails to the users.
  • they send e-mails after register, reset password and credentials change
    procedure (user ID and/or e-mail).
  • they also support sending custom e-mails after custom events.
• both dbConnectors and mailConnectors allow appending custom handler functions,
  either to modify the default ones or providing completely new functionalities.

To sum up, newly introduced functions/classes and their deprecated ancestors:

• RegLogServer class replaces login_server
• RegLog_login_UI function replaces login_UI
• RegLog_register_UI function replaces register_UI
• RegLog_resetPass_UI function replaces password_reset_UI
• RegLog_credsEdit_UI function introduces credential edit UI functionality.
• RegLogDBIConnector class replaces login_server(db_method = "sqlite") and
  widen the usability
• RegLogGsheetConnector class replaces login_server(db_method = "gsheet")
• RegLogEmayiliConnector class replaces login_server(email_method = "emayili")
• RegLogGmailrConnector class replaces login_server(email_method = "gmailr")
• RegLog_txt function replaces reglog_txt
• DBI_tables_create function replaces create_sqlite_db with added functionality
• gsheet_tables_create replaces create_gsheet_db
• RegLogConnectorMessage function to parse your own messages to connectors
• RegLogConnector class to inherit from during creation of your own connectors

Deprecated without direct replacement:

• logout_button: using RegLogServer$logout() method creating own logout
  logic is straightforward.
• sqlite_get_db and gsheet_get_db: getting tables and sheets is straightforward
  using functions from DBI or googlesheets4 packages