massive refactoring to switch from camelCase to snake_case:

historically, Libervia (SàT before) was using camelCase as allowed by PEP8 when using a
pre-PEP8 code, to use the same coding style as in Twisted.

However, snake_case is more readable and it's better to follow PEP8 best practices, so it
has been decided to move on full snake_case. Because Libervia has a huge codebase, this
ended with a ugly mix of camelCase and snake_case.

To fix that, this patch does a big refactoring by renaming every function and method
(including bridge) that are not coming from Twisted or Wokkel, to use fully snake_case.

This is a massive change, and may result in some bugs.

sat/plugins/plugin_xep_0059.py

@@ -51,10 +51,10 @@ class XEP_0059(object):
     def __init__(self, host):
         log.info(_("Result Set Management plugin initialization"))
 
-    def getHandler(self, client):
+    def get_handler(self, client):
         return XEP_0059_handler()
 
-    def parseExtra(self, extra):
+    def parse_extra(self, extra):
         """Parse extra dictionnary to retrieve RSM arguments
 
         @param extra(dict): data for parse
@@ -102,7 +102,7 @@ class XEP_0059(object):
             data["index"] = rsm_response.index
         return data
 
-    def getNextRequest(
+    def get_next_request(
         self,
         rsm_request: rsm.RSMRequest,
         rsm_response: rsm.RSMResponse,