CPLGetValueType(): do not recognize '01' as integer, but as string

[rouault]

Fixes Toblerity/Fiona#1454

[coveralls]

coverage: 69.434% (-0.002%) from 69.436%
when pulling 84d127a on rouault:CPLGetValueType_01
into 1571b1b on OSGeo:master.

[theroggy]

@rouault small question (no underlying request for change)... I wondered, for this type of automatic detection of types, is it typically the first row of data that is inspected, or all rows, or a few rows?

[rouault]

I wondered, for this type of automatic detection of types, is it typically the first row of data that is inspected, or all rows, or a few rows?

It depends on drivers. The GML driver will do a full scan. The CSV driver doesn't do type detection by default, but has options to enable it and limit the number of scanned bytes.