Renamed LLVMBuilder to LLVMIRBuilder to make naming consistent with coming LLVMDIBuilder

LLVM type system refactored to use a subclass per kind. This models LLVM types bit more object-oriented as type-specific methods such as access to parameter/member types is implemented in specific classes only. The FFI callouts still return a generic LLVMType, which later changes its class during it's initialization (see LLVMType>>initialize). Added some tests for types.

Added DIBuilder API to LLVM C Ext library The DIBuilder API is shamelessly copied & modified from LLVM's GO bindings (see bindings/go/llvm in LLVM sources)

Added LLVM's LICENSE.TXT to llvm_c_ext. Updated READMEs.

Added support for intrinsics. As access to intrinsics is not exposed by LLVM-C API, a custom C++ library exposing those hase been added - llvm_c_ext. Smalltalk binds to this library in addition to LLVM's. In a future this library will expose whatever C++ API will be needed in scope of this project. However, it's designed to usable standalone, i.e., it contains no Smalltalk-specic code.

Added an example of iterative factorial function It does not check for integer overflow as that would require using an intrinsic (which are not yet supported)

Added example for compiling conditional. Added convenience API to simply code generation.

Introduced class LLVMConfig to abstract a particular LLVM version

Added inspector tab to show generated assembly for a module as generated by LLVM's `llc` static compiler.

Refactored 'Hello World' example to ise GEP. This way, the example is statically-compilable by `llc` compiler.