Add warnings in a separate file too.

This commit configures the logger so that when a log file is
requested, another file with the suffix `_warnings` is added,
containing only the warnings. The warnings are still being placed in
the log file as well. The file name for the warnings file takes care
of any file extensions, even when there are periods in the file name
itself before the file extension. Extra spaces and color formatting is
removed from the warnings so that the log file doesn't contain escape
sequences used for coloring the terminal output.

pelicun/base.py

@@ -289,11 +289,18 @@ def __init__(self, verbose, log_show_ms, log_file, print_log):
 
         if log_file is None:
             self.log_file = None
+            self.warning_file = None
         else:
             try:
-                filepath = Path(log_file).resolve()
-                self.log_file = str(filepath)
-                with open(filepath, 'w', encoding='utf-8') as f:
+                path = Path(log_file)
+                self.log_file = str(path.resolve())
+                name, extension = split_file_name(self.log_file)
+                self.warning_file = (
+                    path.parent / (name + '_warnings' + extension)
+                ).resolve()
+                with open(self.log_file, 'w', encoding='utf-8') as f:
+                    f.write('')
+                with open(self.warning_file, 'w', encoding='utf-8') as f:
                     f.write('')
             except BaseException as err:
                 print(
@@ -396,6 +403,14 @@ def emit_warnings(self):
         for message in self.warning_stack:
             if message not in self.emitted:
                 warnings.warn(message, PelicunWarning)
+                if self.warning_file is not None:
+                    with open(self.warning_file, 'a', encoding='utf-8') as f:
+                        f.write(
+                            message.replace(Fore.RED, '')
+                            .replace(Style.RESET_ALL, '')
+                            .replace(self.spaces, '')
+                        )
+
         self.emitted = self.emitted.union(set(self.warning_stack))
         self.warning_stack = []
 
@@ -445,6 +460,18 @@ def print_system_info(self):
 pelicun_path = Path(os.path.dirname(os.path.abspath(__file__)))
 
 
+def split_file_name(file_path: str):
+    """
+    Separates a file name from the extension accounting for the case
+    where the file name itself contains periods.
+
+    """
+    path = Path(file_path)
+    name = path.stem
+    extension = path.suffix
+    return name, extension
+
+
 def control_warnings():
     """
     Convenience function to turn warnings on/off

pelicun/tests/test_base.py

@@ -206,6 +206,18 @@ def test_logger_div():
         os.remove('log.txt')
 
 
+def test_split_file_name():
+    file_path = "example.file.name.txt"
+    name, extension = base.split_file_name(file_path)
+    assert name == 'example.file.name'
+    assert extension == '.txt'
+
+    file_path = "example"
+    name, extension = base.split_file_name(file_path)
+    assert name == 'example'
+    assert extension == ''
+
+
 def test_print_system_info():
     # create a logger object
     log_config = {