Improvement of LikeFilter with accent

[ng-galien]

I've found the LIKE filter can be improved with french langage because it have accent. (like in the demo dataset).

The original implementation unaccent the uppercase result.
The following query on the base_unit table

SELECT (unaccent(UPPER(name))) FROM public.base_unit;

returns

unaccenttext
--
UNITe
PIeCE
BOiTE DE 2 PCES

We can see that UPPER does not affect accented characters. (Unité -> UNITé)
The following query returns a much better result

SELECT (LOWER(unaccent(name))) FROM public.base_unit;

lowertext
--
unite
piece
boite de 2 pces

I don't know if it has side effects on the entire application.
I'm testing that modification in com.axelor.rpc.filter, first tests are concluant on base unit conversion form.

@Override
  public String getQuery() {
    if (DBHelper.isUnaccentEnabled()) {
      return String.format(
          "LOWER((unaccent(%s))) %s LOWER(unaccent(?)))", getOperand(), getOperator());
    }
    ....
  }

NB: PostgreSQL 11.1 on x86_64-apple-darwin13.4.0, compiled by Apple LLVM version 6.0 (clang-600.0.57) (based on LLVM 3.5svn), 64-bit

[axeloradmin]

Thanks, we'll consider the change in next release.