Fixes and refactoring

[kraftpunk97-zz]

This PR contains fixes for the problems I encountered while preparing the demo for my JSoC report. It fixes the following issues...

• floor was applied to the low fields of the Box space, instead of ceil. This fixes an issue where we may occasionally get an out-of-bound value for something like Box(1.1, 3.4, Int32).

• The spaces are seldom used directly by the user. Exporting them to main API interface, which should only be for the functions that are used on a constant basis, is not the right choice. Therefore, those exports have been removed, and the environments can call them by the using .Space statement

• Removed the export of contains from Space module, as Base.in has already been overloaded. to call contains

• Fixed an issue where calling the render!() function in :human_pane or :rgb mode would not display immediately in a script.

• Switched the order the train and render_mode arguments in the definition of the make function. User will supply the value of the render_mode argument in more cases than for train, so train will be using its default value more often, and needs to be on the right side.

[kraftpunk97-zz]

@tejank10 Committing a second batch of fixes. Here is a summary of the notable changes...

• Reordered the arguments in the signature of contains to match it with Base.in. contains def of Spaces that are collections of other spaces was modified to use Base.in.

• Tried to fix the Box equality issue as discussed in #21. Two Box Spaces with different dtypes have been considered equal if they're Integers and either both are signed or both unsigned. Int16 Box space has been assumed to be equal to an Int8 box; reason being that they represent the same set of numbers, but using different number of bytes (UInt8(3) == UInt16(3) evaluates to true).

[kraftpunk97-zz]

@tejank10 added the requested changes. Please try to overlook the commit history mess. I ended up pushing the wrong commit to the wrong branch and that led to all kinds of trouble. Git wasn't being very nice.

[tejank10]

Nice work, @kraftpunk97 !