Add functions to compute a developer's last activity

[bockthom]

Prerequisites

• I adhere to the coding conventions (described here) in my code.
• I have updated the copyright headers of the files I have modified.
• I have written appropriate commit messages, i.e., I have recorded the goal, the need, the needed changes, and the location of my code modifications for each commit. This includes also, e.g., referencing to relevant issues.
• I have put signed-off tags in all commits.
• I have updated the changelog file NEWS.md appropriately.
• I have checked whether I need to adjust the showcase file showcase.R with respect to my changes.
• The pull request is opened against the branch dev.

Description

While we already have functionality to compute the first activity per developer, there was no functionality yet to compute the last activity per developer. With this PR, functionality to compute the last activity per developer is added.

Changelog

Added

• Add function to compute last activity per person and activity type
• Add function to add vertex attribute "last.activity"

[maxloeffler]

@bockthom I have had a closer look at the changes submitted in this PR and I could not find major issues with it! I only spotted some minor stylistic ones, I will list them below.

[maxloeffler]

Thank you @bockthom for correcting the misalignments all over util-networks-covariates.R! I only spotted three tiny misalignments that slipped through (see below). Apart from those, I approve this PR.

[maxloeffler]

The elements in the aggregation.level c(...) are not one space off:

coronet/util-networks-covariates.R

Lines 938 to 943 in 4a593dc

	add.vertex.attribute.author.role.function = function(list.of.networks, project.data, classification.function,
	name = "author.role",
	aggregation.level = c("range", "cumulative", "all.ranges",
	"project.cumulative", "project.all.ranges",
	"complete"),
	default.value = NA) {

Same goes for the elements in the aggregation.level c(...) here:

coronet/util-networks-covariates.R

Lines 635 to 642 in 4a593dc

	add.vertex.attribute.author.issue.comment.count = function(list.of.networks, project.data,
	name = "issue.comment.count",
	aggregation.level = c("range", "cumulative", "all.ranges",
	"project.cumulative",
	"project.all.ranges", "complete"),
	default.value = 0L,
	issue.type = c("all", "pull.requests", "issues"),
	use.unfiltered.data = FALSE) {

Lastly, these parameters are just overall off:

coronet/util-networks-covariates.R

Lines 1147 to 1151 in 4a593dc

	add.vertex.attribute.artifact.last.edited = function(list.of.networks, project.data, name = "last.edited",
	aggregation.level = c("range", "cumulative", "all.ranges",
	"project.cumulative",
	"project.all.ranges", "complete"),
	default.value = NA) {

Note: As you did not edited these lines, it would not let me create a regular review comment and I had to resort to this.

[bockthom]

I've fixed the three misalignments that you have spotted @maxloeffler (at least, I hope so). If all the misalignments you have spotted are fixed now and if you agree with my descriptions in the NEWS.md, I'd be happy if you could also formally approve this PR 😄