Frontend + Backend / Appointment tables: Add dropdown list with global options

[Theophilix]

Use case: A massage studio offers "thai; full body; leg; back; shoulder; hot stone" massage. So, on the same height like the "book appointment" button, the user can choose those values from a dropdown list: "Choose your option". So, if the user chooses "thai" for example, the system reloads the selected table and offers the dates and times available for the option "thai".

What should be done:
In backend, we should add the function "add option list" / with "yes" and "no". If "yes" is selected a small table opens (two columns of 5 rows with input forms). In the left column (description "Enter global options:" [ger: "Optionen eintragen:"]), the user types in values in a text form, for example "thai". In the right column, the users chooses the corresponding table (description "Choose corresponding table:" [ger: "Korrespondierende Tabelle auswählen:"]) via dropdown list :
thai ---- thaitable1
hot stone ---- hotstone_NewTable etc.
[For this, we need a column called "corresptable" in mysql]

In backend, we need also:

1. the variable "{option}" for the confirmation text. That way, the admin can send an automated email with the sentence "you chose the option {option}. Your appointment is at {time} on {date}." Furthermore, the admin can send himself a ics, so he/she knows, which option the user has chosen - very important info for the admin here!

2. the option to "show selected option to user" yes/no [ger: "Zeige ausgewählte Option dem Admin"] "show selected global option to admin" [ger: "Zeige ausgewählte Option dem User" ]. So the admin can see in the table, which user selected which option, for example: "Mister X (selected option)"

In frontend, below the date and time selection info, we need the sentence: "selected option:"

XML Import / Export: When importing xml, check if all corresponding tables do exist. If not, change option "add option list" automatically to "no" .

CSV Export: Option is always exported behind the name in parentheses, for example: "Mister X (selected option)".
CSV Import: Extract option from last word in parentheses in string, if user wants to import text like Mister X (my neighbour) (selected option)"

[Theophilix]

added in 4.7.6 version