style: merge data_types/src/types/* into data_types/src/types.vhd

[umarcor]

Currently, there are two files with 5 lines each. When byte_vector is added in #507, there will be three. Apart from being short, the content is tightly related. As proposed in #507, a single types_pkg package is defined, and all the types are put there.

Moreover, as commented in #507, the definition of byte_t is moved from verification_components/**/memory_pkg.vhd to this data_types/**/types.vhd.

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Also, in #507, type storage_mode_t is (internal, extfnc, extacc); is defined in string_ptr_pkg.vhd. This type is to be later used by integer_vector_ptr_pkg.vhd (#476) and memory_pkg.vhd (#470). Therefore, it makes sense to make byte_t and storage_mode_t available in a similar fashion.

[umarcor]

@LarsAsplund, I updated this issue and I believe it is ready to merge. However, there is something strange going on with Travis.

• The latest commit in this PR is fd89519.
• The corresponding Travis run on my fork is https://travis-ci.com/dbhi/vunit/builds/128416931, which is all successful.
• The commit is automatically merged with master, producing 32a89e2.
• The corresponding Travis run (which is shown below) is https://travis-ci.org/VUnit/vunit/builds/587195514, and it is failing just as the latest commit pushed by @kraigher: https://travis-ci.org/VUnit/vunit/builds/587167948.

This is very strange because this PR is not rebased on top of master yet. Therefore, even if the latest commit in master is broken, this PR should succeed (as it does on my fork).

EDIT

I replied to myself.. the commit is automatically merged with master