start requiring >= boost 1.47 to enable things like the carto parser to be integrated soon

INSTALL.md

@@ -37,10 +37,7 @@ Build dependencies are:
 Mapnik Core depends on:
 
  * Boost
-    - >= 1.46 is recommended
-    - >= 1.45 is required if compiling with clang++
-    - >= 1.42 works on most systems and most compilers
-    - >= 1.47 is required to support wkt/wkb geometry output (optional)
+    - >= 1.47 is required.
     - These libraries are required:
       - filesystem
       - system

SConstruct

@@ -44,7 +44,7 @@ SCONS_CONFIGURE_CACHE = 'config.cache'
 SCONF_TEMP_DIR = '.sconf_temp'
 # auto-search directories for boost libs/headers
 BOOST_SEARCH_PREFIXES = ['/usr/local','/opt/local','/sw','/usr',]
-BOOST_MIN_VERSION = '1.41'
+BOOST_MIN_VERSION = '1.47'
 CAIROMM_MIN_VERSION = '1.8.0'
 
 DEFAULT_LINK_PRIORITY = ['internal','other','frameworks','user','system']