Feature/use git info cache for all solution projects (#191)

* GitIsDirty.cache should be overwritten instead of appended

* add the possibility to overwrite the path where the caches are placed

src/GitInfo/build/GitInfo.targets

@@ -64,6 +64,13 @@
 					 in a previous build in a GitInfo.cache for
 					 performance reasons.
 					 Defaults to empty value (no ignoring).
+					 
+  $(GitCachePath): where to cache the determined Git information
+				   gives the chance to use a shared location
+				   for different projects. this can improve
+				   the overall build time.
+				   has to end with a path seperator
+				   Defaults to empty value ('$(IntermediateOutputPath)').
 
 	$(GitTagRegex): Regular expression used with git describe to filter the tags 
 					to consider for base version lookup.
@@ -110,6 +117,7 @@
     <GitSkipCache Condition="'$(GitSkipCache)' == ''">false</GitSkipCache>
     <SkipReadGitCache Condition="'$(SkipReadGitCache)' == ''">$(GitSkipCache)</SkipReadGitCache>
     <SkipWriteGitCache Condition="'$(SkipWriteGitCache)' == ''">$(GitSkipCache)</SkipWriteGitCache>
+    <GitCachePath Condition="'$(GitCachePath)' == ''">$(IntermediateOutputPath)</GitCachePath>
 
     <GitCommitsIgnoreMerges Condition="'$(GitCommitsIgnoreMerges)' == ''">false</GitCommitsIgnoreMerges>
 
@@ -141,10 +149,10 @@
     </CoreCompileDependsOn>
 
     <!-- Cache file used to avoid running all git commands. Only GitRoot will be retrieved to determine the path of this cache file. -->
-    <_GitInfoFile>$(IntermediateOutputPath)GitInfo.cache</_GitInfoFile>
+    <_GitInfoFile>$(GitCachePath)GitInfo.cache</_GitInfoFile>
 
     <!-- Stores value of GitIsDirty variable from last execution, file is changed when the value changes betwee runs. -->
-    <_GitIsDirtyFile>$(IntermediateOutputPath)GitIsDirty.cache</_GitIsDirtyFile>
+    <_GitIsDirtyFile>$(GitCachePath)GitIsDirty.cache</_GitIsDirtyFile>
   </PropertyGroup>
 
   <Target Name="GitInfoReport" DependsOnTargets="GitInfo;GitVersion">