Improve error message when failing to load gmt library #792
Description
Description of the problem
See this post for context.
When PyGMT fails to load the GMT library, it doesn't provide useful information so it's unclear what causes the failure.
Actually, ctypes.CDLL provides some useful information, for example:
import ctypes
ctypes.CDLL("/path/to/libgmt.so")
gives me more information:
OSError Traceback (most recent call last)
<ipython-input-8-7c08c5dbc028> in <module>()
----> 1 CDLL("/usr/local/lib/libgmt.so")
/usr/lib/python3.6/ctypes/__init__.py in __init__(self, name, mode, handle, use_errno, use_last_error)
346
347 if handle is None:
--> 348 self._handle = _dlopen(self._name, mode)
349 else:
350 self._handle = handle
OSError: /usr/lib/x86_64-linux-gnu/libstdc++.so.6: version `GLIBCXX_3.4.26' not found (required by /usr/local/lib/././libtiledb.so.2.1)
We should let PyGMT output these messages.