Update spelling "mbed TLS" to "Mbed TLS"

The official spelling of the trade mark changed from all-lowercase "mbed"
to normal proper noun capitalization "Mbed" a few years ago. We've been
using the new spelling in new text but still have the old spelling in a
lot of text. This commit updates most occurrences of "mbed TLS":

```
sed -i -e 's/mbed TLS/Mbed TLS/g' $(git ls-files ':!ChangeLog' ':!tests/data_files/**' ':!tests/suites/*.data' ':!programs/x509/*' ':!configs/tfm*')
```

Justification for the omissions:

* `ChangeLog`: historical text.
* `test/data_files/**`, `tests/suites/*.data`, `programs/x509/*`: many
  occurrences are significant names in certificates and such. Changing
  the spelling would invalidate many signatures and tests.
* `configs/tfm*`: this is an imported file. We'll follow the upstream
  updates.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 52814ba..b001bb7 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -34,18 +34,18 @@
 cmake_policy(SET CMP0012 NEW)
 
 if(TEST_CPP)
-    project("mbed TLS" C CXX)
+    project("Mbed TLS" C CXX)
 else()
-    project("mbed TLS" C)
+    project("Mbed TLS" C)
 endif()
 
 # Set the project root directory.
 set(MBEDTLS_DIR ${CMAKE_CURRENT_SOURCE_DIR})
 
-option(USE_PKCS11_HELPER_LIBRARY "Build mbed TLS with the pkcs11-helper library." OFF)
-option(ENABLE_ZLIB_SUPPORT "Build mbed TLS with zlib library." OFF)
+option(USE_PKCS11_HELPER_LIBRARY "Build Mbed TLS with the pkcs11-helper library." OFF)
+option(ENABLE_ZLIB_SUPPORT "Build Mbed TLS with zlib library." OFF)
 
-option(ENABLE_PROGRAMS "Build mbed TLS programs." ON)
+option(ENABLE_PROGRAMS "Build Mbed TLS programs." ON)
 
 option(UNSAFE_BUILD "Allow unsafe builds. These builds ARE NOT SECURE." OFF)
 option(MBEDTLS_FATAL_WARNINGS "Compiler warnings treated as errors" ON)
@@ -57,9 +57,9 @@
 
 # the test suites currently have compile errors with MSVC
 if(CMAKE_COMPILER_IS_MSVC)
-    option(ENABLE_TESTING "Build mbed TLS tests." OFF)
+    option(ENABLE_TESTING "Build Mbed TLS tests." OFF)
 else()
-    option(ENABLE_TESTING "Build mbed TLS tests." ON)
+    option(ENABLE_TESTING "Build Mbed TLS tests." ON)
 endif()
 
 # Warning string - created as a list for compatibility with CMake 2.8