doc: add release documentation for Homebrew formula
doc: move grn_ctx_open() document to Sphinx text from header file
Bump up version number to 3.0.7

3.0.6 ->
3.0.7

% make update-version NEW_VERSION=3.0.7
Merge pull request #64 from whombx/grn-ctx-open

doc: move grn_ctx_open() document to Sphinx text from header file
Allocate result place after WITH_SPSAVE()

WITH_SPSAVE() keeps result place as a garbage object on stack. So the
result place should be allocated after WITH_SPSAVE().
Hide internal function
Fix a crash bug

It causes by offline index construction for vector column that has
orphan reference. Groonga should avoid the case (e.g. groonga returns
an error for removing table that is referred from any column) but
this fix will be useful a bit to make groonga more robust.
Add dangling hook reference check

Normally, the case is not occurred. (So I couldn't add a test for the
case. :<) It makes groonga more robust.
test: add a missing test

It is for 788312a0a8d6dd013933c84524c937fb0ed69bd6:

    Fix a crash bug

    It causes by offline index construction for vector column that has
    orphan reference. Groonga should avoid the case (e.g. groonga returns
    an error for removing table that is referred from any column) but
    this fix will be useful a bit to make groonga more robust.
Extract db remove code
Fix parameter order
Extract code that removes patricia trie table
test: fix extension for expected result
Extract code that removes double array trie table
Extract code that removes hash table
Use expanded name instead of abbreviated name

Because of consistency. Other tests use expanded name.

dat ->
double_array_trie
Use expanded name instead of abbreviated name

Because of consistency. Other tests use expanded name.

pat ->
patricia_trie
Extract code that removes array table
Extract code that removes variable size column
Extract code that removes fix size column