Fixes MultiPoint::fromWKT() so it works with alternate no nested parenthesis wkt

[opengisdev]

Sorry for not discussing this problem before doing the PR :(

WKT officially supports two syntaxes for MultiPoint, one with nested parenthesis and one without:

MULTIPOINT ((10 40), (40 30), (20 20), (30 10))
MULTIPOINT (10 40, 40 30, 20 20, 30 10)

https://en.wikipedia.org/wiki/Well-known_text_representation_of_geometry

laravel-postgis only supports the nested parenthesis syntax.
Postgis st_astext unfortunately uses the version without nested parenthesis:

select st_astext(st_geomfromtext('MULTIPOINT((1 1),(2 1),(2 2))'))
would return
MULTIPOINT(1 1,2 1,2 2)

This PR fixes the problem by checking if no nested parenthesis syntax is used, and if so, adding the parenthesis and go on with the rest of the function. This could probably be done in a more elegant way but I'm not that good at regex :( There is a test proving this problem in the PR.

The PR also updates the regex to support floating point values, it replaces \d by [+-]?([0-9]+([.][0-9]*)?|[.][0-9]+) as explained here: https://stackoverflow.com/questions/12643009/regular-expression-for-floating-point-numbers but yet again, I'm far from an expert with regular expressions. There is also a test proving the problem.

Thanks for maintaining this great package!

[JoanBonnin]

Is there any plan to merge this any soon? Also, I'm having some troubles with this specific class, since it's not loading InvalidArgumentException class, so we should also add the use InvalidArgumentException line.

@mstaack

[mstaack]

sure go ahead and add the import statement, i will then merge