Add support for filtering based on property exclusion.

For example, allow commands like:

  # exclude issues from context "abc"
  pit list -C abc

  # exclude issues delegated to John Doe
  pit list -P "delgated-to:John Doe"

src/pit.nim

@@ -167,6 +167,16 @@ proc parsePropertiesOption(propsOpt: string): TableRef[string, string] =
     if pair.len == 1: result[pair[0]] = "true"
     else: result[pair[0]] = pair[1]
 
+proc parseExclPropertiesOption(propsOpt: string): TableRef[string, seq[string]] =
+  result = newTable[string, seq[string]]()
+  for propText in propsOpt.split(";"):
+    let pair = propText.split(":", 1)
+    let val =
+      if pair.len == 1: "true"
+      else: pair[1]
+    if result.hasKey(pair[0]): result[pair[0]].add(val)
+    else: result[pair[0]] = @[val]
+
 proc sameDay(a, b: DateTime): bool =
   result = a.year == b.year and a.yearday == b.yearday
 
@@ -290,6 +300,7 @@ when isMainModule:
   trace "context initiated"
 
   var propertiesOption = none(TableRef[string,string])
+  var exclPropsOption = none(TableRef[string,seq[string]])
   var tagsOption = none(seq[string])
 
   if args["--properties"] or args["--context"]:
@@ -302,6 +313,20 @@ when isMainModule:
 
     propertiesOption = some(props)
 
+  if args["--excl-properties"] or args["--excl-context"]:
+
+    var exclProps =
+      if args["--excl-properties"]:
+        parseExclPropertiesOption($args["--excl-properties"])
+      else: newTable[string,seq[string]]()
+
+    if args["--excl-context"]:
+      if not exclProps.hasKey("context"): exclProps["context"] = @[]
+      let exclContexts = split($args["--excl-context"], ",")
+      exclProps["context"] = exclProps["context"].concat(exclContexts)
+
+    exclPropsOption = some(exclProps)
+
   if args["--tags"]: tagsOption = some(($args["--tags"]).split(",").mapIt(it.strip))
 
   ## Actual command runners
@@ -449,6 +474,11 @@ when isMainModule:
       filter.properties = propertiesOption.get
       filterOption = some(filter)
 
+    # Add property exclusions (if given)
+    if exclPropsOption.isSome:
+      filter.exclProperties = exclPropsOption.get
+      filterOption = some(filter)
+
     # If they supplied text matches, add that to the filter.
     if args["--match"]:
       filter.summaryMatch = some(re("(?i)" & $args["--match"]))
@@ -473,6 +503,7 @@ when isMainModule:
        filter.properties["context"] == "all":
 
       filter.properties.del("context")
+      filter.exclProperties.del("context")
 
     var listContexts = false
     var statesOption = none(seq[IssueState])