vim-patch:8.1.0735: cannot handle binary data

Problem:    Cannot handle binary data.
Solution:   Add the Blob type. (Yasuhiro Matsumoto, closes vim/vim#3638)
6e5ea8d2a9

Nvim-specific Blob conversions are implemented in future commits.

Refactor write_blob() to use a FileDescriptor, as f_writefile() was
refactored to use one (does not apply to read_blob()).

Use var_check_lock() in f_add() for Blobs from v8.1.0897.

Add a modeline to test_blob.vim and fix some doc typos.

Include if_perl.txt's VIM::Blob() documentation. Interestingly, this
function already worked before this port, as it just returns a Blob
string literal, not an actual Blob object.

N/A patches for version.c:

vim-patch:8.1.0741: viminfo with Blob is not tested

Problem:    Viminfo with Blob is not tested.
Solution:   Extend the viminfo test.  Fix reading a blob.  Fixed storing a
            special variable value.
8c8b8bb56c

vim-patch:8.1.1022: may use NULL pointer when out of memory

Problem:    May use NULL pointer when out of memory. (Coverity)
Solution:   Check for blob_alloc() returning NULL.
e142a9467a

src/nvim/api/private/helpers.c

@@ -444,6 +444,9 @@ void set_option_to(uint64_t channel_id, void *to, int type,
 #define TYPVAL_ENCODE_CONV_EXT_STRING(tv, str, len, type) \
     TYPVAL_ENCODE_CONV_NIL(tv)
 
+#define TYPVAL_ENCODE_CONV_BLOB(tv, blob, len) \
+  abort() /* TODO(seandewar) */ \
+
 #define TYPVAL_ENCODE_CONV_FUNC_START(tv, fun) \
     do { \
       TYPVAL_ENCODE_CONV_NIL(tv); \
@@ -584,6 +587,7 @@ static inline void typval_encode_dict_end(EncodedData *const edata)
 #undef TYPVAL_ENCODE_CONV_STRING
 #undef TYPVAL_ENCODE_CONV_STR_STRING
 #undef TYPVAL_ENCODE_CONV_EXT_STRING
+#undef TYPVAL_ENCODE_CONV_BLOB
 #undef TYPVAL_ENCODE_CONV_NUMBER
 #undef TYPVAL_ENCODE_CONV_FLOAT
 #undef TYPVAL_ENCODE_CONV_FUNC_START