Manage deletion of SHP file while opening a database with linked table
Manage deletion of DBF file while opening a database with linked table
Define empty dummy table when shp or dbf files are not available
define(s)
Merge pull request #65 from nicolas-f/fix/linked_shp

Manage deletion of SHP/DBF file while opening a database with linked table

If a linked shape file or dbf file was deleted or moved, it was impossible to reopen the database.
Shape file with null geometry, show specific message
Fix error message
Merge pull request #67 from nicolas-f/fix/error-shpnullgeom

Show specific message for shape files with null geometries
Add ST_MakePoint

```mysql
SELECT ST_MakePoint(1.4, -3.7);
```
Answer:     `POINT(1.4 -3.7)`
```mysql
SELECT ST_MakePoint(1.4, -3.7, 6.2);
```
Answer:     `POINT(1.4 -3.7 6.2)`

*Note*: PostGIS has a fourth signature for geometries with measure:
```mysql
    geometry ST_MakePoint(double precision x, double precision y,
        double precision z, double precision m);
```

See http://postgis.net/docs/manual-1.4/ST_MakePoint.html
Use the keyword NOBUFFER instead of NOCACHE
Update interface property name
Add ST_MakeEllipse

I simplified the signatures allowed in GDMS. Now we have just one
signature:
```mysql
SELECT ST_MakeEllipse(ST_MakePoint(2, -3), 6, 4);
```

In GDMS, the following were available:
```mysql
SELECT ST_MakeEllipse(ST_MakePoint(2, -3), 6, 4);
SELECT ST_MakeEllipse(2, -3, 6, 4);
SELECT ST_MakeEllipse(2, -3, 6, 4, PI()/3);
```

The rotation part can be taken care of by ST_Rotate.
update readme for new version
Merge pull request #71 from nicolas-f/patch_r5331

Use the keyword NOBUFFER instead of NOCACHE
Compare ST_Buffer to ST_MakeEllipse for circles.

The only difference between a circle constructed using `ST_MakeEllipse`
and a circle contructed using `ST_Buffer` is the number of line segments
in the approximation.  `ST_MakeEllipse` is more fine-grained (100
segments rather than 32).
Merge pull request #69 from agouge/st_makepoint

Add ST_MakePoint

```mysql
SELECT ST_MakePoint(1.4, -3.7);
```
Answer:     `POINT(1.4 -3.7)`
```mysql
SELECT ST_MakePoint(1.4, -3.7, 6.2);
```
Answer:     `POINT(1.4 -3.7 6.2)`

*Note*: PostGIS has a fourth signature for geometries with measure:
```mysql
    geometry ST_MakePoint(double precision x, double precision y,
            double precision z, double precision m);
            ```
            But they don't show an example of this. See
            http://postgis.net/docs/manual-1.4/ST_MakePoint.html
Merge pull request #72 from agouge/st_makeellipse

Merge Just one signature is available:
```mysql
SELECT ST_MakeEllipse(ST_MakePoint(2, -3), 6, 4);
```
This creates an ellipse centered at `POINT(2 3)` with width 6 and height 4.

The only difference between a circle constructed using `ST_MakeEllipse`
and a circle contructed using `ST_Buffer` is the number of line segments
in the approximation.  `ST_MakeEllipse` is more fine-grained (100
segments rather than 32).

*Note*: In GDMS, the following signatures were available:
```mysql
SELECT ST_MakeEllipse(ST_MakePoint(2, -3), 6, 4);
SELECT ST_MakeEllipse(2, -3, 6, 4);
SELECT ST_MakeEllipse(2, -3, 6, 4, PI()/3);
```
The rotation part can be taken care of by `ST_Rotate`.
Merge with master