DELTASPIKE-767 Comprehensive review of javadoc: core/api

A non-comprehensive overview of changes (some may be from other commits):
* the term page-bean is rarely used, not used in doc at all, use view-controllers instead
* meta-data -> metadata
* English doesn't use that many dash-separated word compounds, rephrased/undashed/split as necessary
* replace occurrences of vague "the entry" or "current entry" with more descriptive ones like "this view-config"
* replace occ. of PageBean.class with ViewControllerRef.class
* make clear what's an example, e.g. SomePage.class instead of PageConfig.class which sounds like an API class
* page -> view
* "X allows to [infinitive verb]" is a non-existent construct in English syntax. Corrected all occurrences. It's meaningless in an API documentation (javadoc), since every single method "allows" the user to do something.
* Moved TODOs from javadocs to comments
* formatting (120 char line length)
* reorganized ConfigProperty
* less of "we", more passive forms
* refactored BeanProvider's javadoc, warnings about dependent, etc.
* ConversationSubGroup shouldn't only mention conversation closing
* added some links (@see) to enable discovery of features in javadoc
* removed some defensive-sounding design decision arguments ("this class exists because..."), reformulated to convey purpose
* configuration.ordinal -> deltaspike_ordinal
* (Solder) Catch -> Exception Control