Treat declarations of pure virtual functions as definitions.
A pure virtual function won't (usually) have a definition.  Without one, we won't hyperlink
the name of the function where it is called.  As a workaround until we have better support
for (pure) virtual functions, we treat the declaration as a definition.
Merge branch 'testing' of https://github.com/mozilla/dxr into pure-virtual
Merge pull request #68 from abbeyj/testing

Don't emit variable definition entries for things which are only declara...
Merge pull request #69 from abbeyj/pure-virtual

Treat declarations of pure virtual functions as definitions.
Remove "t" prefix from columns in the "types" table.
Remove "f" prefix from columns in the functions table.
Remove "v" prefix from columns in the "variables" table.
Remove "t" prefix from columns in the "typedefs" table.
Record the name and qualname of the typedef and stop recording the underlying type
for now since it is not used.
Remove "w" prefix from columns in the "warnings" table.
Remove "macro" prefix from columns in the "macros" table.
Remove "s" prefix from columns in the "scopes" table.
Rename the "ID" column in the "files" table to "id" (lowercase)
Fix typo of "d" instead of "id" for column in "functions" table.
Remove prefixes and other brain-deadness from SQL column names. Closes #71.