GitLab

Instead of manually defining the target to copy pablo source files
to the cache directory, can now use parabix_add_pablo_src.

Kernel tests created with the `parabix_add_kernel_test` function
are automatically added to `make check`.

+ switched all add_library calls to parabix_add_module

Not sure if pablo.bixnum is a good name for this module, but this can be
changed later if need be.

- \p regular expressions are currenly broken
- need to debug on linux as lldb is giving weird issues with icgrep

To resolve depdencies between ucd and re, more functionallity will be
moved to the ucd modules. As such, a more generic name should be given
to these libraries as they won't just be responsible for the unicode
database anymore.

- created new modules re.alphabet and re.toolchain
- broke apart some files into multiple ones in different modules
- decomposed re_toolchain.cpp (WIP: by the end, this file will no longer exist)
- note: still need to removed re.compile's dependency on ucd.data