Not compatible with python3

When using with python3:

```
>>> import googleearthplot
Traceback (most recent call last):
File "", line 1, in
File "/home/nvidia/.local/lib/python3.6/site-packages/googleearthplot/__init__.py", line 1, in
from googleearthplot import googleearthplot
File "/home/nvidia/.local/lib/python3.6/site-packages/googleearthplot/googleearthplot.py", line 26
print "[PlotLineChartFromCSV] plotting a line chart from csv file:"+filepath
^
SyntaxError: Missing parentheses in call to 'print'. Did you mean print("[PlotLineChartFromCSV] plotting a line chart from csv file:"+filepath)?
```

Start by reproducing the Python 3 import failure and inspect googleearthplot/googleearthplot.py at line 26, along with the package entry point shown in the traceback. Check whether the package imports successfully under Python 3 and whether the existing plotting functionality still runs without Python 2 syntax errors.

Written by the indexing model from the issue text.