Implemented function calls from lambdas, stored variables and expressions

What type of change does this PR perform?

[ ] Info or documentation change (Non-breaking change that updates repo info files (e.g. README.md, CONTRIBUTING.md, etc.) or online documentation)
[ ] Website (Change that changes the design or functionality of the websites or docs)
[ ] Development or internal changes (These changes do not add new features or fix bugs, but update the code in other ways)
[ ] Bug fix (Non-breaking change which fixes an issue)
[x] New feature (Non-breaking change which adds functionality)
[ ] Breaking change (Major bug fix or feature that would cause existing functionality not to work as expected.)
[ ] Requires a documentation update, as it changes language or compiler behaviour

Implemented function calls from lambdas, stored variables and expressions so that any expression that returns a function can be called.

Closes #674

Not present for website/docs changes

Support for calling lambdas and functions stored in variables or expressions. (#674)

CLI command run not properly reporting internal or unexpected errors, as they were already prettified in the internally called up command compile.

None.