Add proper logging mechanism to application

This mechanism has custom coloring, support to dump in file and
on the commandline and support to turn either or both off. cli/cli.py
provies a function that can be called in each module to instantiate
a logger for that module.

srdl2sv/log/log.py

@@ -0,0 +1,59 @@
+import logging
+from typing import Optional
+
+class CustomFormatter(logging.Formatter):
+    """Logging Formatter to add colors and count warning / errors"""
+
+    MAPPING = {
+        'DEBUG'   : 37, # white
+        'INFO'    : 32, # green
+        'WARNING' : 33, # yellow
+        'ERROR'   : 31, # red
+        'CRITICAL': 41, # white on red bg
+    }
+
+    PREFIX = '\033['
+    SUFFIX = '\033[0m'
+
+    def format(self, record):
+        colored_record = record
+        levelname = colored_record.levelname
+        seq = CustomFormatter.MAPPING.get(levelname, 37) # default white
+        colored_levelname = ('{0}{1}m{2}{3}') \
+            .format(
+                CustomFormatter.PREFIX,
+                seq,
+                levelname,
+                CustomFormatter.SUFFIX)
+        colored_record.levelname = colored_levelname
+
+        return logging.Formatter.format(self, colored_record)
+
+def create_logger (
+        mod_name,
+        stream_log_level: int = logging.WARNING,
+        file_log_level: int = logging.INFO,
+        file_name: Optional[str] = None):
+
+    log = logging.getLogger(mod_name)
+    log.setLevel(min(stream_log_level, file_log_level))
+
+    if file_log_level > 0 and file_name:
+        file_handler = logging.FileHandler(file_name)
+        file_handler.setLevel(file_log_level)
+
+        file_formatter = logging.Formatter(
+            "%(asctime)s - %(levelname)s - %(name)s: %(message)s")
+        file_handler.setFormatter(file_formatter)
+        log.addHandler(file_handler)
+
+    if stream_log_level > 0:
+        stream_handler = logging.StreamHandler()
+        stream_handler.setLevel(stream_log_level)
+
+        stream_formatter = CustomFormatter(
+            "[%(levelname)s][%(name)s] %(message)s")
+        stream_handler.setFormatter(stream_formatter)
+        log.addHandler(stream_handler)
+
+    return log