DataLoader - validate table name

[nikg]

Data Loader: Before throwing an error "XYZ is not a valid Table Name" after you click "Start", validate that the table name is named correctly:

Table names may contain only alphanumeric characters.
Table names cannot begin with a numeric character.
Table names are case-insensitive.
Table names must be from 3 to 63 characters long.

These rules are also described by the regular expression "^[A-Za-z][A-Za-z0-9]{2,62}$". Table names preserve the case with which they were created, but are case-insensitive when used.