Improve error messages for failed expressions

fixes #8076
Implement support for lambdas

refs #8030
Remove obsolete unit test

refs #8040
Fix operator precedence for =>

refs #8030
Implement the 'global' keyword to differentiate between variable scopes

refs #8074
Backport i2tcl's error reporting functionality into "icinga2 repl"

fixes #8078
Make sure Serialize() doesn't fail for objects which don't have a registered type

fixes #7895
Refactor how variable scopes work

refs #8074
Only implicitly convert strings to indexers

refs #8074
Allow if/else in rterms

refs #8074
Make sure IcingaApplication::GetVars returns a default value

refs #8074
Remove unused code

refs #8074
Disable impersonation for the "repl" command

refs #7805
Remove unnecessary includes
Docs: Update dependency state filter explaination

refs #7301
Docs: Fix gdb pretty printers

fixes #8048
Fix incorrect variable scoping

refs #8074
Cli: "node wizard" shouldn't crash when SaveCert fails

fixes #7707
Fix unit test

refs #8074
Get rid of the local/global keywords

refs #8074