Expand configuration (#368)

* Allow configuring httpMaxConns

default: 100

* Allow setting NITTER_CONF_FILE path env var

Co-authored-by: 3nprob <3nprob@3nprob>

src/types.nim

@@ -204,6 +204,7 @@ type
     address*: string
     port*: int
     useHttps*: bool
+    httpMaxConns*: int
     title*: string
     hostname*: string
     staticDir*: string