Serialize and deserialize database

[gwenn]

Fix #880
Port of Tcl impl
Partial duplicate of #786

[codecov]

Codecov Report

Patch coverage has no change and project coverage change: -0.01 ⚠️

Comparison is base (38bf316) 80.67% compared to head (67d1e34) 80.67%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1341      +/-   ##
==========================================
- Coverage   80.67%   80.67%   -0.01%     
==========================================
  Files          49       49              
  Lines       10085    10084       -1     
==========================================
- Hits         8136     8135       -1     
  Misses       1949     1949              

Impacted Files	Coverage Δ
src/error.rs	26.85% <ø> (-0.42%)	⬇️
src/lib.rs	84.32% <ø> (ø)

☔ View full report in Codecov by Sentry.
📢 Do you have feedback about the report comment? Let us know in this issue.

[gwenn]

@thomcc would you mind reviewing this minimum viable API ?
You should be able to serialize the data anywhere (disk / network) (with the Deref<[u8]> impl).
But to deserialize, users will need sqlite3_malloc / sqlite3_realloc...
(maybe we will be able to provide a nicer API when std::alloc:: Allocator is stable)

[thomcc]

This looks basically reasonable to me, sorry for the delay, I missed this in my inbox until now.

[dimo414]

Any plans for a 0.30 to pick up this PR? Would love to use it!