Created a page to add/remove IMAP E-Mail accounts
Updated E-Mail account setting page
Converted replies from custom comments to custom posts

Also changed the usage of word comment/comments with reply/replies
Added CSRF protection in Email account setting page
Removed SupportFlow_Email_Accounts::get_email_accounts method allowing direct data access
Splitted SupportFlow_Email_Accounts::settings_page in multiple smaller methods
Made minor changes to E-Mail accounts settings page

Renamed is_exist_email_account method with email_account_exists
Corrected I18n format using sprintf
Used esc_attr instead of esc_html for escaping attributes
Fixed implementation of sanitize_text_string
Using variables instead of a fixed value for slugs
Add option to choose SSL ports in E-Mail account setting page
Checking SSL option on by default in E-Mail accounts add form
Using intval() to sanitize integer field
Fix remove E-Mail account form submission for firefox/IE
Added description to class and file
Corrected whitespace
Add labels to form elements
Using WP selected() function to output checked attribute
Using variables to store imap/smtp ssl preference
Prefixing table elements with 'table_' to avoid mutiple elements with same ID
Set account data to null instead of removing it to maintain unique account ID
Corrected IMAP_INVALID_CREDENTIALS constant spelling