Update CHANGELOG for 4.8.0.

Author: jehugaleahsa

CHANGELOG.md

@@ -1,3 +1,8 @@
+## 4.8.0 (2020-09-17)
+**Summary** - Avoid memory leaks by creating new dynamic assemblies each time.
+
+I was not sure how much of a runtime impact creating a new dynamic assembly would be and so I was trying to optimize the code by storing the `AssemblyBuilder`/`ModuleBuilder` in a static variable. However, I had no mechanism in place to prevent generating duplicate types/methods each time a reader/writer was created, so over time the same emitted code was being added to the dynamic assembly over and over again; a.k.a., a memory leak. At first I tried to implement some sort of caching but then realize that it was almost impossible to uniquely identify a type/column mapping configuration without looking at every property on every mapping. I decided to try creating new assemblies each and every time and that I ran a benchmark. There was no discernable difference in performance, so I think eliminating the premature optimization is the right approach.
+
 ## 4.7.0 (2020-02-15)
 **Summary** - Support capturing trailing text after last fixed-length window.
 

FlatFiles/FlatFiles.csproj

@@ -10,17 +10,17 @@
     <RepositoryUrl>https://github.com/jehugaleahsa/FlatFiles.git</RepositoryUrl>
     <RepositoryType>git</RepositoryType>
     <PackageTags>csv;comma;tab;separated;value;delimited;flat;file;fixed;width;fixed-width;length;fixed-length;parser;parsing;parse</PackageTags>
-    <PackageReleaseNotes>Support capturing trailing text after last fixed-length window.</PackageReleaseNotes>
+    <PackageReleaseNotes>Avoid memory leaks by creating new dynamic assemblies each time.</PackageReleaseNotes>
     <SignAssembly>true</SignAssembly>
     <AssemblyOriginatorKeyFile>FlatFiles.snk</AssemblyOriginatorKeyFile>
-    <Version>4.7.0</Version>
+    <Version>4.8.0</Version>
   </PropertyGroup>
 
   <PropertyGroup>
     <LangVersion>8.0</LangVersion>
     <PackageIconUrl>https://raw.githubusercontent.com/jehugaleahsa/FlatFiles/master/icon.png</PackageIconUrl>
-    <AssemblyVersion>4.7.0.0</AssemblyVersion>
-    <FileVersion>4.7.0.0</FileVersion>
+    <AssemblyVersion>4.8.0.0</AssemblyVersion>
+    <FileVersion>4.8.0.0</FileVersion>
     <PackageLicenseFile>UNLICENSE.txt</PackageLicenseFile>
   </PropertyGroup>