Reintroduced small MavenProject instances cache

MavenProject instances cache size is hardcoded to 5 and it is
meant to improve incremental build performance. From limited
and not very scientific testing, trivial m2e-maven-runtime
incremental build takes ~130ms without the cache and <30ms with
the cache.

Signed-off-by: Igor Fedorenko <igor@ifedorenko.com>
2 files changed