data inspection: additional checks and warning messages

[newgene]

For the inspection feature implemented in #107, let's include these additional checks and display or highlight identified warnings:

• flag a field name if it contains whitespace (e.g. sometime we see a dev creates a key like "gene name" instead of "gene_name" or "genename")
• flag a field name if it contains upper cased letter or special characters (lower-cased is recommended, in some cases the upper-case field names are acceptable, so we should raise it as a warning and let user to confirm it's necessary)
• also flag a field name when the type inspection detects more than one types (but a mixed or single value and an array of same type of values are acceptable, or the case of mixed integer and float should be acceptable too)
• to display these warnings, in your types & stats tab, I think you can show the stats of warnings on the top, and then highlight the field name row in the table with some badge icons and a tooltip msg.