Fix muddled namespaces and prevent integrating them from other packages

[Martin-Jung]

Loading the package (CTRL+SHIFT+L) places the functions from all imported or dependend packages into the ibis.iSDM own namespace.
To reproduce:

• Check available functions via ibis.iSDM:: (and press < TAB > ), showing functions such as extract from raster or INLA-related functions.

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Similar but likely directly related bug:
Helpfiles from the ibis.iSDM package are not loaded. For instance after loading the package ?distribution does not point to the distribution function but instead to stats::distribution

[matthewlewis896]

Possibly this is related to the change of package name - I've just noticed that sometimes we're using package = "ibis" and othertimes package = "ibis.iSDM". Going to dig into this more and see if that may be responsible.

Help page for distribution loads from ibis.iSDM for me and renders correctly. I only get the stats help page when trying ?stats::distribution and the ibis.iSDM when just using ?distribution

[Martin-Jung]

Requesting the namespace directly fixed the issue. See 122f5a5
Can potentially be done for other dependencies as well but should be mandatory for all engines