Basic fromproj4 works, except need better handle when unprojected (longlat and latlong)

Also just need to expand to more projection name, datum name, and
ellipsoid name definitions, and also additional special parameters.

After that, test, and move onto from_wkt()...

pycrs/webscrape.py

@@ -0,0 +1,77 @@
+import urllib2
+import re
+
+def build_crs_table(savepath):
+
+    # create table
+    outfile = open(savepath, "wb")
+    
+    # create fields
+    fields = ["codetype", "code", "proj4", "ogcwkt", "esriwkt"]
+    outfile.write("\t".join(fields) + "\n")
+    
+    # make table from url requests
+    for codetype in ("epsg", "esri", "sr-org"):
+        print(codetype)
+        
+        # collect existing proj list
+        print("fetching list of available codes")
+        codelist = []
+        page = 1
+        while True:
+            try:
+                link = 'http://spatialreference.org/ref/%s/?page=%s' %(codetype,page)
+                html = urllib2.urlopen(link).read()
+                codes = [match.groups()[0] for match in re.finditer(r'/ref/'+codetype+'/(\d+)', html) ]
+                if not codes: break
+                print("page",page)
+                codelist.extend(codes)
+                page += 1
+            except:
+                break
+
+        print("fetching string formats for each projection")
+        for i,code in enumerate(codelist):
+            
+            # check if code exists
+            link = 'http://spatialreference.org/ref/%s/%s/' %(codetype,code)
+            urllib2.urlopen(link)
+            
+            # collect each projection format in a table row
+            row = [codetype, code]
+            for resulttype in ("proj4", "ogcwkt", "esriwkt"):
+                try:
+                    link = 'http://spatialreference.org/ref/%s/%s/%s/' %(codetype,code,resulttype)
+                    result = urllib2.urlopen(link).read()
+                    row.append(result)
+                except:
+                    pass
+
+            print("projection %i of %i added" %(i,len(codelist)) )
+            outfile.write("\t".join(row) + "\n")
+
+    # close the file
+    outfile.close()
+
+            
+def crscode_to_string(codetype, code, format):
+    link = 'http://spatialreference.org/ref/%s/%s/%s/' %(codetype,code,format)
+    result = urllib2.urlopen(link).read()
+    return result
+
+def crsstring_to_string(string, newformat):
+    # search string, if string is correct there should only be one correct match
+    link = 'http://spatialreference.org/ref/?search=%s' %string
+    searchresults = urllib2.urlopen(link).read()
+    # pick the first result
+    # ...regex...
+    # go to its url, with extension for the newformat
+    link = 'http://spatialreference.org/ref/%s/%s/%s/' %(codetype,code,newformat)
+    result = urllib2.urlopen(link).read()
+    return result
+    
+
+if __name__ == "__main__":
+    build_crs_table("crstable.txt")
+
+