Improve performance by invoke KFunction by "call".

[k163377]

Pull request for Issue #403.

Additional

From reading the Branches in the README, I thought this change would be for 2.13, but since 2.13 doesn't seem to exist at present, I'm tentatively sending a pull request for 2.12.
Fixed.

TODO: Appropriate branch settings and CLA submission

done.

[cowtowncoder]

I just created 2.13. It's up to @dinomite and @viartemev to determine where this should go, depending on likelihood of regressions, but 2.13 branch now exists (as of 8 hours ago or so)

[k163377]

I will close when #439 is merged.

[dinomite]

I'll be looking at this and the other PRs (#438, #439) over the next few days. I think 2.13 is probably the best place for them.

[dinomite]

I'm unable to get mvn compile to work—the change to the sources directory has made it so that the compiler plugin can't find the package version which is generated by the com.google.code.maven-replacer-plugin:

[ERROR] Failed to execute goal org.jetbrains.kotlin:kotlin-maven-plugin:1.4.21:compile (compile) on project jackson-module-kotlin: Compilation failure
[ERROR] /Users/dinomite/Dropbox/code/misc/jackson-module-kotlin/src/main/kotlin/com/fasterxml/jackson/module/kotlin/KotlinModule.kt:[37,18] Unresolved reference: PackageVersion

I pushed to a branch in the main repo, so that CircleCI could run, which shows the full error.

[k163377]

@dinomite
As far as I have tried locally, the following changes seemed to work, so please check them (also reflected in #439).
d26df02

Since the content of this PR largely conflicts with #439 and is less effective, I thought it would be better not to merge it.
As for the review, I would appreciate it if you could give priority to #438 and #439.

[k163377]

This change will be merged in #538.