Input data validation error messages have changed

Improved input data validation process was added in 7.x-1.8. This change introduces new validation error message and might affect:

• Multilingual websites: new validation message must be translated
• Websites which override validation message(s): change in override logic is required

Before 7.x-1.8 there were possible 2 validation error messages for float/decimal fields:

 - Only numbers and the decimal separator (@separator) allowed in %field.
 - %field: There should only be one decimal separator (@separator).

Starting 7.x-1.8 there there are only 1 validation error message that combines both errors:

 - Only numbers and one decimal separator (@separator) allowed in %field.