Improve getPoints() + explode() performance for large geometries

[babldev]

Issue
For geometries with 10k+ points, it can take 10+ seconds on a modern machine to call getPoints() or pointInPolygon().

Root Cause
The points array was built using array_merge(), which gets more complex (n^2) as the array gets larger.

Fix
Use simple array appending instead of array_merge()

Before:

$ time ../vendor/bin/phpunit tests/largeInputTest.php 
real    0m13.354s
user    0m13.318s
sys 0m0.030s

After:

$ time ../vendor/bin/phpunit tests/largeInputTest.php 
real    0m0.194s
user    0m0.172s
sys 0m0.016s

[babldev]

Tests passed here phayes#127

[danielhochman]

+1